Note: my source for new terms has stopped sending me daily email messages, so for now this page will not be updated unfortunately.
The information here has been gathered from the online version of Smart Computing Magazine daily emails, which I subscribe.
Content management software lets you manage Web content. Using such software, you can quickly update specific Web pages, remove content, or add new content to your Web site without any technical expertise such as HTML knowledge. A CMS typically consists of a content management application (CMA) and a content deliver application (CDA).
CERN, which is short for the European Organization for Nuclear Research (or Conseil Europeenne pour la Recherche Nucleaire), performs several different types of research in its Geneva, Switzerland, headquarters. Those who developed the Web interface, Tim Berners-Lee and Robert Cailliau, both were scientists at CERN when they developed the Web in late 1990. Berners-Lee generally receives the bulk of the credit for conceiving and developing the Web with some help from Cailliau. (Keep in mind the Web is a communications system that exists on the Internet; it's not the same thing as the Internet, although many people use the two terms synonymously.)
Berners-Lee, a computer scientist at CERN, originally conceived of the Web as a method for sharing information concerning high-energy physics experiments between physicists working all over the world. No one knew the Web would be the favorite hangout for tens of millions of Internet users within 10 years.
Berners-Lee worked with Cailliau to write the first Web browser and editor software. They also wrote software for the first Web server and defined the communications protocols, such as URLs (uniform resource locators), HTML (Hypertext Markup Language), and HTTP (Hypertext Transfer Protocol). For Berners-Lee, the key element of the Web protocols was to ensure they were easy to use and didn't exclude any type of computer from participating. He felt it was vital that any type of computer running any type of software could run Web protocols.
Although a nuclear research laboratory might seem like a strange place for creating the Web, it was a natural solution to a problem at CERN. CERN is an international organization where about 6,500 scientists from more than 80 countries visit to perform research. It is one of the world's largest scientific laboratories. CERN performs scientific research on a number of fronts, focusing on laws of matter and on experiments concerning particle physics.
Because the scientists collaborating on various projects needed a visual medium over which to share data and because they used computers extensively, communicating using computers over the Internet seemed natural. However, in the late 1980s, communicating across the Internet had plenty of obstacles. The variety of computers and networks in use made smooth communications difficult. Scientists became frustrated with the amount of time they had to spend to make the electronic communications methods work properly. Berners-Lee's development of the Web at CERN filled a growing need by standardizing communications methods for the Internet.
Berners-Lee initially proposed the concept of the Web in 1989. He and Cailliau refined it and had a workable, basic demonstration system by the end of 1990. To encourage CERN scientists to use the Web interface, Berners-Lee made sure to incorporate the ability to view existing documents and Usenet newsgroups within the Web browser. This backward compatibility was a key component for adoption of the Web at CERN.
With the overwhelming presence the Web currently enjoys, it might seem hard to believe that the Web was in its infancy just one decade ago. After its creation, several components had to fall into place before the Web could enjoy widespread use. After completion of the early components of the Web, CERN and Berners-Lee posted the functions to the CERN program library early in 1991, giving universities and research laboratories around the world access to them. By 1993, more than 50 Web servers were up and running. However, with limited resources available to further develop the Web and to develop more user-friendly Web browser technology, Berners-Lee put out a plea for help from other developers. With the idea for the Web in hand, Marc Andreessen and NCSA (National Center for Supercomputing Applications) developed a graphics-based Mosaic browser, which eventually became available for Macintosh computers and PCs. As Mosaic's use began to spread across the world, more and more information became available on the Web. Consequently, the Web's usage also grew, much faster than almost anyone envisioned.
Although CERN doesn't focus on computer technology research, it does operate a massive computer network at its headquarters, consisting of nearly 10,000 desktop computers all running through a powerful network of servers. And, through its high-speed Internet connections, CERN scientists can collaborate with colleagues around the world.
CERN, founded in 1954, provides scientists with state-of-the-art research facilities. Beyond the Web, scientists at CERN are responsible for dozens of inventions and discoveries that have led to advancements in cancer therapy, medical imaging, industrial imaging, food preservation, and destruction of toxic products. Several amazing research tools are available at CERN, including a particle accelerator that is more than 16 miles around and in which particles travel near the speed of light. CERN also owns the world's largest magnet, which weighs more than the Eiffel Tower.
A group of servers used to balance heavy request loads coming into a single DNS (domain name server) and IP (Internet Protocol) address. Instead of forwarding all Web browser requests for a page’s content to a single server, the requests are spread out among several machines for that specific URL (universal resource locator). Web farm setups are also good for providing content and service backup in case one server in the group fails.
Provides additional information about variables within programs. Before Hungarian notation was widely used, programmers often forgot important details about a variable, such as its data type (a data type determines what you can and cannot do with a variable). Charles Simonyi, a Microsoft programmer, developed the method of notation that requires programmers to place a three-letter prefix before a variable name. Therefore, a list box entitled “Files” might be called “lstFiles” so the programmer would know the variable refers to a list box. The convention is widely used within Microsoft and its development community.
A halftone is a printing term that refers to a copied image that is rendered in black-and-white (or another single shade) by means of reproducing it in dots of varying size or concentration. Halftones are created from continuous-tone pictures, such as a photograph where the shades and images are seamlessly blended together. For instance, a dark area in a picture represented in halftone is created by large dots spaced closely together.
Most laser printers, which don’t have the capacity to reproduce images using differently sized dots, use a technique called dithering to create halftones. Dithering means that the printer simulates different shades by spacing the dots closer together for a darker look or spacing them farther apart for a lighter appearance. The human eye naturally fills in the space between the dots to make the area look blended, much as a pointillist painting from a distance looks as if it were created with smooth brush strokes.
Frederic Eugene Ives [1856-1937] is attributed with the invention of halftone technology, which he revealed to the public in 1888. He achieved the photomechanical process by photographing an image through a screen. The density of the mesh would determine how clear or grainy the final product would appear, which is measured in lines per inch. DP (desktop publishing), on the other hand, doesn’t use screens; it just simulates the photographic process. Some programs even require the user to specify a screen frequency even though there is no such equipment in sight.
Halftones are monochromatic by definition, but you can use them to reproduce full-color pictures. In traditional printing, four halftone plates of an image are rendered in yellow, cyan, magenta, or black. When laid over one another, the dots merge together in the viewer’s eye and the image appears to have all the same shades as the original.
Newspapers, magazines, and other printed matter from letterpress, offset, rotogravure, or silk-screen processes use the halftone technique to deliver images. In DP, halftones are usually used for artistic effect.
Communication in which data bits don't need to wait for a certain event or time to be transmitted. Telephone communication is one example because both parties can speak at the same time. Synchronous transmission, on the other hand, occurs at regular, structured intervals. Most of the communication between a computer and a device, such as a printer or a modem, is asynchronous; communication within a computer system generally is synchronous because it is regulated by the microprocessor. Because of the freedom involved in asynchronous transmissions, a computer system must determine the starting and stopping points of a string of transmitted data with data bits known as start and stop bits. Compare to synchronous transmission.
Abandonware is a designation given to software that developers no longer support or sell. Old arcade and console games generally are labeled as abandonware, as are old computer games and outdated applications. Abandonware should not be confused with freeware, which the authors or owners intended to be free from the outset, nor should it be confused with shareware, which is created to make a profit. Abandonware is commercial software that once sold for a price and is no longer available.
The Internet has magnified the issues surrounding abandonware by making it easier to distribute, but all Internet users should be aware that it is illegal to download most of the abandonware you find online. Although the software may no longer be supported or sold in stores, the individuals who own the rights to the software still have the right to distribute it as they see fit.
The fact also remains that a company potentially can begin selling its old software again, and abandonware distribution in the meantime will cut into any future profits it would receive by doing so. For these reasons and many more, most companies are sending cease and desist letters to the leading abandonware sites and occasionally taking legal action to protect their software. The IDSA (Interactive Digital Software Association) is perhaps the most proactive antipiracy group trying to stop the spread of illegal abandonware, but individual companies, such as Nintendo, also police the Internet and attempt to shut down sites illegally distributing copies of their software.
Sometimes designers, developers, or people with the rights to distribute their software grant the computing community rights to copy and distribute their old commercial titles, and this is the only circumstance where obtaining abandonware is legal.
An acronym for describing storage media such as a DVD as double-sided high-density.
A chip architecture that provides the microprocessor with the capability to process more than one instruction in every clock cycle.
An infrared data transmission that can reach 115 kilobits per second. SIR is part of the IrDA 1.1 standard.
An encryption term that refers to normal text prior to encryption (a process that transforms normal, readable text into coded text that cannot be read without the assistance of specific encryption software) and following decryption. The term cleartext can be used interchangeably with the term plaintext. See decryption. See encrypt.
A modem that uses your cable TV connection instead of a phone line to connect to the Internet. Because the bandwidth of coaxial cable is much higher than that of the standard phone line your telephone company uses, the speed advantage of cable modems versus regular phone modems is profound. Cable modem speeds range from 500Kbps to 10Mbps. The top speed of phone modems, by comparison, is almost 10 times slower, at 53Kbps. Cable modems' highest speeds are for downloading; you won't be able to send data nearly as fast because cable TV networks are designed primarily to send information out to homes. Overall speed also varies widely because bandwidth on a cable TV network is a shared resource. If everyone on your block signs up for cable modem service and downloads large files, the available bandwidth--and speed--will drop dramatically. Most cable modems are currently external models that connect to a computer via an Ethernet port. Compare to Asymmetric Digital Subscriber Line (ADSL).
Seat is a term often used in business software licenses. A seat refers to number of users a license supports at any one time. If you license software for ten seats and eleven people are using the software, you’re violating your software license and need to purchase an additional seat.
Fonts that simulate rough handwriting. Many script fonts really do look much like someone’s scribbles, but the eveness of the spacing gives away the fonts' digital origins.
A simple program that activates when a computer has been inactive for a specified period of time. Screen savers, often moving image or graphic displays, were originally designed to prevent images from being burned into monochrome monitors. Any image left unchanged on a monochrome monitor for an extended length of time ran the risk of leaving a permanent imprint. Today's new monitors no longer run the risk of having their screens imprinted by images, but screen savers are still popular for their entertainment value.
A clear film that covers a PDA or desktop computer screen to protect it from scratches and dust. Screen protectors are also available for screens on other items such as MP3 players, cell phones, or GPS navigation devices and usually last between one and three months.
Refers to a computer monitor's ability to display a range of shapes without distortion. Many monitors do a poor job of reproducing polygons and other shapes.
The appearance of a flicker or unsteadiness in an image on a monitor's screen. The flicker can have several causes. If the refresh rate is too slow for the application currently running, the image is not being redrawn quickly enough to display the most current image. Low-persistence phosphors are more likely to cause flicker.
The process of copying information found on a Web page, such as an email address, into a database or other program. Spammers sometimes employ robot software (sometimes referred to as bot, crawler, or spider software) to scrape email addresses found on the Internet.
Term applied to the actual structure of a database, usually used to describe the graphical interface such as tables, columns, or fields.
On a video monitor, this is the number of vertical or horizontal sweeps per second.
Refers to the beam projected by the electron gun in a traditional CRT (cathode-ray tube) monitor.
The part of a scanner that moves over an image and then scans it.
The higher the contrast in a scanned image, the bigger the span between black values and while values.
In a scanner, this is the area to which movement of the scan head is limited.
A particularly bright color that, when displayed on a monitor, tends to “bleed” at its edges, which results in a blurry image.
In Twitter, the commercial “at” symbol (@) goes in front of a person’s username to create a link to the person’s profile page. Many tweets will include multiple @usernames to call out friends, co-workers, customers, prize winners, and other Twitter users.
If you see a tweet (a Twitter post) that you would like to share with your followers, you can retweet it. When you retweet, a small retweet icon will appear at the bottom of the post, along with your username. Some users add "RT" to retweets to make it clear that the post is a retweet. The "RT" acts as symbol rather than a command; you don’t need to use it to retweet. You can click the Retweet icon in Twitter to retweet a message.
An online seminar. Such Web conferences are often interactive: the person giving the seminar can receive live input from the people in virtual attendance. Webcasts, on the other hand, are generally one-way presentations.
A hashtag (#) is used in Twitter (and sometimes on other social media sites) to designate a keyword. It’s meant to help people (who are searching for posts on the same topic) to find your post. For example, you might put a hashtag in front of “computer” (#computer) when you tweet about repairing your business’ workstation. People searching for #computer will see your tweet.
An Internet meme is an image, phrase, video, that not only goes viral, but is adopted by users across the Internet. An example is the lolcat: an image of a cat, along with a caption that is supposedly written by the cat. Public relations teams sometimes attempt to create Internet memes that feature certain products.
Short for "permanent link," a permalink is a URL (uniform resource locator) that isn’t expected to change. You may encounter a permalink when you are reading a news piece on a website’s main page, for example. The main page will replace that piece with new content soon, so you’ll want to follow the permalink and bookmark that link if you intend to return to it.
In social networks, your profile is your presence on the network. Many social networks have a profile page that includes a biography, images of you , and any other information you’d like to share. Keep this sharing in mind as you fill out such profiles; many profiles give you the opportunity to provide personal contact information. Sharing that sort of information with the public can lead to spam an junk mail.
In Twitter, a direct message is a private message that you send to a specific user. It isn’t shared with your followers.
Percentage of time that a machine, component, or computer periperhal is actually in use. The lifespan of a product may be roughly estimated based on its duty cycle. The lifespan of the product is measured in total hours of use and may exceed 1,000,000 hours.
A list of data contained in a computer's memory when a program is prematurely terminated. The data list is either saved to diskette or sent directly to a printer. A dynamic dump lets program developers track what is happening in the memory during any given moment in the execution of an application.
In a GUI (graphical user interface), a menu that is opened when the menu name is clicked, letting the user choose one command from a list of several options. The File menu of a word processing document is an example of a drop-down menu.
A phrase used to describe languages and systems that make use of objects, or distinct pieces of data. Object-oriented programming features reusable, somewhat standardized code pieces linked together to create new applications.
Wire speed refers to the physical speed support by a wire. Wire speed can be used when describing hardware, however. Switches, routers, and other networking hardware are said to run at wire speeds if they can operate at the same speed as the wire.
This is the term used most frequently to describe a computer that is not connected to the Internet. When you’re working offline, you’re not connected to or actively browsing on the Internet. This term also describes a computer within a network that is not connected to the computer network at that time. Another Internet-related meaning for the term “offline” relates to offline browsers or readers. These software programs let users download e-mail and information from Web sites and browse the material after disconnecting from the online service. Being able to read Internet transmitted data while offline may save the user online fees and free up her phone lines.
Hardware components, such as printers or scanners, may be connected to a system and may even be turned on, but if they’re not in the Ready mode, they’re considered offline. Often, some kind of an error sends a printer offline.
The term can also refer to storage. Offline storage usually refers to the floppy diskettes, discs, Zip disks, and tapes of computer data stored in a physical library.
Adjusting the size of the space between lines to make the top and bottom margins equal. This feature is found mostly in word processing and desktop publishing software.
Refers to the number of fields placed on a monitor screen per second.
In computing, 3-D graphics are created by combining numerous triangles to form a desired shape. The term “vertex” typically refers to the individual points or corners of these triangles—the points where two sides of a triangle meet. These vertices are, in fact, the very “virtual matter” that creates a 3-D object.
When a graphics card processes an object, the card receives information on all of the vertices used to build it. Each vertex carries information about the 3-D coordinates x, y, z, and w (weight). Color information is often specified in the form of a diffuse as well as a specular color, and then coded in the RGBA (red, blue, green, and alpha) format. One or more coordinates representing the texture and position for the vertex are also supplied, along with fog effect and point size information, and the vector that points orthogonal off the vertex’s surface. Although the vertex is the smallest unit in a 3-D image, it carries a tremendous amount of information.
Certain graphics processing units offer what is called the vertex shader as a graphics processing function that is capable of adding special effects to objects within a 3-D scene. It accomplishes this by performing mathematical calculations on the objects’ vertex data. As mentioned above, vertices carry data about color, coordinates, textures, lighting, and more. Vertex shaders do not actually change the type of data related to a vertex; they simply change the values so that a vertex appears on-screen with a different color, texture, or position. This process enables realistic movements, motion blur, blending, morphing, and so forth.
Vertex skinning (sometimes called vertex blending) is a technique used in 3-D graphics. It lets programmers blend the edges of computer-generated shapes at their vertices. Vertex skinning takes care of the miniscule gaps often found between the joints of a 3-D character. The triangles and vertices that make up these parts of an image can be blended where they intersect with each other.
A slang term used to describe a software program or piece of hardware that is plain or has very few added features.
A unique name assigned to a storage medium, usually at the time it is formatted. DOS-based systems rarely use volume labels, but Macintosh systems frequently refer to them on-screen as volume names.
Software designed to perform certain housekeeping tasks, such as those related to managing system resources (such as diskette drives and printers) and file capabilities (such as sorting and copying). Utilities also can be used to diagnose a problem on a PC. Utilities are usually installed as memory-resident programs permanently stored in memory.
The amount of storage on a storage medium, or the name of the medium itself. A single diskette, for example, may contain several volumes, as in situations where a hard drive is partitioned into several drives, each of which is a volume.
This term is often used to describe a type of keyboard key. A linear key offers consistent resistance to your finger as you press it. Many, if not most, keyboards have linear keys. An alternative is the tactile key, which provides peak resistance part of the way through the key press. The resistance signals to the typist that the key has been pressed far enough for the character to register; fast typists take advantage of this by not pressing the key any farther and moving on to the next key. Tactile keys are also helpful for typists who “pound” their keyboards.
Marks on a page that help ensure all elements are aligned properly.
In a paint program, the act of filling in an area with a specific color or pattern.
Reformat is a term used to describe the process of re-initializing a floppy diskette or hard drive. When you reformat a floppy diskette, the data on the diskette is erased, and the diskette is then initialized to the type of computer operating system you’re using. For example, not all computer operating systems read data off floppy diskettes in the same way. Windows-based computers can’t read diskettes formatted for a Macintosh and vice versa unless a third-party program is used to interpret how the data is stored on the floppy. Without the third-party program, the operating system will think the diskette is bad and should be reformatted. Many store-bought floppy diskettes come preformatted by the diskette manufacturer for a particular type of computer. So if you mistakenly purchase preformatted diskettes for a Macintosh and you have a Windows-based computer, you will have to reformat all of them before you can use them on your computer.
When it comes to hard drives, there are two types of reformatting. One is called a low-level reformat, and the other is called a high-level reformat. The most common of the two is a high-level reformat. A high-level reformat on a hard drive works exactly like reformatting a floppy diskette. All the data on the drive is erased, and it’s initialized to the type of operating system you are using. Where a high-level reformat only erases user data from the hard drive, a low-level reformat removes all physical information about the hard drive from the drive itself.
The physical information about the hard drive contains information such as how many sectors, cylinders, and tracks are on the hard drive. Physical information also includes the type of disk controller the hard drive is accessing. Most modern hard drives (IDE [Integrated Drive Electronics]- and SCSI [Small Computer Systems Interface]-based) come low-level formatted by the hard drive manufacturer. It’s not recommended for a novice computer user to perform a low-level reformat on a hard drive because if it’s done inocorrectly, your hard drive will become useless, and you’ll have to either send it back to the manufacturer to reset its settings or take it to a reputable computer repair shop in the hope that they can reset the drive.
A way of signifying that certain text has been edited. Redlined text isn't necessarily marked in red; it can appear in any color, or in bold, so long as it stands out from the other text. This technique is used to distinguish text added or changed by one user in a document that is being worked on by two or more people. For instance, Microsoft Word's Revision mode lets one or more people make editing suggestions to a file. The changes made can be shown on-screen and/or on the hard copy, with a particular color used for each person.
To send input or output through a device other than the one usually used for that operation. For example, output can be redirected so a saved file goes to the A: drive instead of the C: drive.
Raster, in relation to computer displays, is a rectangular pattern of lines traced by an electron beam to create an image called horizontal scan lines. Raster is short for raster scan. Rasters appear on both TV screens and computer monitors. The raster is slightly smaller than the physical dimensions of the display screen. Also, the raster varies for different resolutions. For example, a VGA (Video Graphics Array) resolution of 640 x 480 on a 15-inch monitor produces one raster. An SVGA (Super Video Graphics Array) resolution of 1,024 x 768 produces a slightly different raster.
Most monitors can sense the size of the raster and automatically use the optimal raster depending on the monitor’s size and the video adapter’s resolution. In addition, most monitors have controls that let the user move the raster, resize it, and even rotate it. A raster graphic, also known as a bit-mapped graphic, is a type of graphic that consists of rows and columns of dots that make up the image. The value of each dot is stored in one or more bits of data.
Raster graphics are often compared to vector graphics: Vector images are generated by using mathematics to determine the position, length, and direction in which the lines of the image are to be drawn. Unlike raster graphics, which are made up of millions of mapped dots, vector graphics are composed of a collection of lines. A raster graphic file is usually larger than a vector graphic file because it contains all the information about the image within rather than being calculated upon viewing or printing. Raster graphics are more difficult to manipulate than vector graphics because in a raster graphic, you’re working with each dot that makes up the image instead of working with the one formula that draws the lines of a vector graphic. Examples of raster graphics file types include BMP (bitmap), GIF (Graphics Interchange Format), JPEG (Joint Photographic Experts Group), and PNG (Portable Network Graphics).
Term associated with raster:
RIP (raster image processor): In order to print vector-based images, you’ll need a RIP (raster image processor). This is a device that converts vector images into raster graphic or bit-mapped images. RIPs compute the brightness and color value of each pixel on the page based on the vector graphic’s calculations so that the resulting pattern of pixels re-creates the graphic and text as originally described in the vector image. All Postscript printers contain a RIP that converts Postscript command into raster-based pages that the printer can output. RIPs are also used to enlarge images for printing, phototypesetting, or electrostatic plotters. They use special algorithms, such as error diffusion, to enlarge images without sacrificing clarity.
A computer graphic technique used to render photographic-quality, realistic images. Radiosity is based on dividing an image into smaller polygons, or patches, to determine shadow and light patterns when creating images from 3D models. Unlike ray tracing, which follows rays of light between a light source and the objects it illuminates, radiosity takes into account both the light emitted from a light source and the light reflected by all objects in the image’s environment. That is, radiosity accounts not only for a source of illumination (such as a light bulb) but also for the effects of that illumination as it is absorbed by, and reflected from, every object in the “picture.”
Radiosity, sometimes known as secondary illumination, takes into account that the surface light from a reflection is a source of light within a picture. The amount of light a surface produces is based on the texture of the surface. For example, a wall color in a matted material will reflect less light than a wall with a glossy material.
Cindy Goral, Kenneth Torrance, and Donald Greenberg introduced this technique in a paper entitled “Modeling the Interaction of Light Between Diffuse Surfaces” at Cornell University in 1984. They derived the first radiosity image from a thermal engineering technique of the same name that was popular in the 1960s. Radiosity is one of the cornerstones of global illumination techniques for rendering physically realistic images.
Radiosity has become an integral part of many computer games and motion picture special effects. Many computer game developers are using radiosity to provide a greater sense of photorealistic imagery and depth to their games. If radiosity techniques were not used in computer games, games such as Quake, Project Gotham Racing, and Final Fantasy X would look very two-dimensional. The game player would feel that there was a lack of detail and depth to what he was seeing on the screen. Many of the game developers who have an understanding of radiosity program their own radiosity engines to work in conjunction with 3D-enabled video cards in your computer, such as the graphics engine built in third-person 3D game Max Payne.
If radiosity techniques were not used in special effects in movies, many of the background images, set props, and explosions would not have any real depth to them, and their presence would defeat their purpose in the movie. This is because the human eye is sensitive to the absence of radiosity in a three-dimensional image. Your brain will let you know when an image you’re looking at is not real. This is why many special effects studios such as Lucas Digital’s Industrial Light + Magic and animation studios such as Pixar Animation Studio are constantly working on computer programs to offer more realistic effects.
The proliferation of the PC has brought desktop publishing to the masses. Having a license to publish brochures, newsletters, and Web pages doesn’t mean that everyone should, though. Some things, such as page layout, sometimes are best left to the experienced user.
Layout is the pattern or arrangement by which a user places the elements of a publication on the document itself. Those elements can consist of a variety of items, including text blocks, headlines, photographs, and graphical images.
The layout the publisher creates should determine which elements on the page he would like to emphasize. A good page layout also should organize the information through proximity and alignment, and it should be visually appealing. Graphical elements, color usage, and type styles are also important components in layout. A poor layout can hinder the publisher’s attempts to make his message understood. Several books, magazines, and Web sites are available to help you with design principles. Of course, everyone has his idea of what makes a visually appealing layout, but following a few basic design and layout principles will give you a better chance of success.
Fortunately, for those of us who have limited design and layout skills, nearly every type of publishing software contains tips, hints, and templates to help you create appealing, useful layouts. In Microsoft Word, for example, you can set type size, font, line spacing, and text alignment to create a layout that organizes your text in a much more visually appealing manner than using a single kind of text can. Presentation and publishing software packages are especially helpful in providing templates that fit a variety of topics and situations. All you have to do is enter your text and graphical elements in the positions that the template indicates.
Layout and design are especially important for Web pages because visitors need to be able to navigate the site easily. Visitors also want to be able to quickly decipher the information at your site. If Web visitors find the site’s layout too difficult to use or understand, they’ll jump to another site as quickly as they can click a mouse.
Although you can use the term launch in several different computer-related contexts, it nearly always refers to starting a process. Starting a piece of computer software commonly is called launching the software; in this instance, launch is synonymous with run or execute. For example, most OSes (operating systems) launch automatically when you turn on your computer.
Windows 98 includes a Quick Launch Toolbar, which contains buttons that give users quick launch access to commonly used programs, such as Microsoft Internet Explorer. The Quick Launch Toolbar is just to the right of the Start button on the toolbar. You can add buttons to the Quick Launch Toolbar by dragging files onto it. Remove buttons by dragging them to the Recycle Bin.
Many computer companies use the term launch to describe the release of a new software or hardware product. Companies often will hold launch parties for employees and members of the media to publicize the new product. When a company or individual releases a new or redesigned Web site to the public, the site is relaunched.
Latency is the delay between the moment you make a request from a computer’s storage device and the moment the storage device has located the data and is ready to deliver it. Essentially, latency is wasted time because other computer components must wait for the data before they can work again.
Nearly every piece of computer hardware related to data storage and retrieval, including hard drives, network connections, and memory chips, experiences some type of latency. Of course, the computer’s latency isn’t like the latency you experience waiting in the doctor’s office or for the final minute of an NBA game to end; computer hardware latency usually is over within a small fraction of a second.
One common form of latency occurs with your computer’s RAM. RAM latency, usually called CAS (column address strobe) latency, measures the amount of time it takes the RAM to find and deliver data from memory to the microprocessor. CAS latency involves a miniscule amount of time—it’s usually measured in nanoseconds, or billionths of a second—but CAS latency can cause a drag on the performance of the microprocessor while it waits for data from memory. Another common form of latency, called rotational latency, occurs within the hard drive. Rotational latency measures the amount of time it takes the hard drive’s platters to find and deliver the requested data. Smaller rotational latency measurements allow the hard drive to deliver its data more quickly. Again, rotation latency only involves a small fraction of a second—newer hard drive platters typically spin at 10,000rpm (revolutions per minute)—but even small delays can hinder the performance of the microprocessor.
In networking, latency is used to describe the amount of time a packet of data needs to travel from the source to the destination.
Allows users to edit and then save files.
In a transmission, any data or application preceding and/or following a bigger, more important program or chunk of information that helps launch or run the main application successfully. For example, the http:// part in a Web address could be described as a preceding wrapper for the URL address that follows. Wrappers are also used to determine authorization for users who want to change or view the “wrapped” information or program.
A group of computers connected with networking hardware and software so users working toward a common goal can share resources, such as an accounting department or marketing division information. Workgroups can be connected to other workgroups in a larger network structure or can stand alone as separate, mininetworks.
The automatic placement of words on a new line when they reach the right margin of a document and are too large to fit on the current line but, if moved to the next line in their entirety, would leave a blank space on the previous line. If an automatic hyphenation feature is turned on, a portion of a word may be placed on one line, split with a hyphen, and continued on the next line.
A bordered area on-screen that contains an application or document, often used in GUIs (graphical user interfaces) such as Microsoft Windows or Apple Macintosh. Each window can be enlarged, reduced, or minimized to an icon, which temporarily removes it from view. A window provides for multitasking (meaning several programs can be run at once) and lets users cut, copy, and paste information from one window to another. Additionally, windows can be arranged side-by-side (tiled) so that the user can see the full window for a document or application, or overlaid so that the front-most window is seen in full while only the title bars show for windows in the background (called cascading). Windows are enlarged or reduced by clicking on zoom buttons in the far upper-right corner of a display. When an application is open, there is another zoom button (similar in appearance to the aforementioned ones) that resizes a document window within a program, letting the user see, for example, several Microsoft Word files at once. Reduced windows can be resized further by placing the mouse pointer on their borders, pressing the left mouse button, and dragging to the desired position.
Miniwindows often referred to as "floating palettes" because they are always on top of other windows, such as a document or page layout window, and can be moved anywhere on-screen. Generally lacking title bars and minimize/maximize buttons, they do have close icons. Common examples include the Control Palette in PageMaker or the Trap Information palette in Quark XPress.
A description for the layering of windows, one on top of the other, on the display of a windows-based OS (operating system). Compare tiling.
Often used to represent some generic product, as in "Company ABC sells widgets." In programming terminology, a widget is a combination of a graphical component of an application and some programming (a scroll bar or checkbox are common examples of widgets). The widget has a defined look and function. Although it’s possible to create widgets from scratch, most graphical environments come with a predesigned set of widgets that let programmers quickly plug visual components into their applications.
Created at MIT in the 1950s, Whirlwind was the first electronic digital computer. Also the first to use magnetic core memory.
The code name for Microsoft's Windows XP operating system, based on the Windows NT kernel. Originally set to debut in March 2001, Whistler was first called Neptune before Microsoft combined it with another operating system called Odyssey. The result, Windows XP, was released on October 25, 2001.
Named after Whetstone, England. A floating point operation benchmark ("Whetstones per second").
The characters, including spaces, tabs, and characters, that only appear as blanks in on-screen or printed text. In desktop publishing, white space is a section of a page that is unused by text, graphics, or other design elements. White space often is used as a design element to call attention to other objects on a page or to prevent objects from appearing crowded.
A hacker who breaks into a computer system for the thrill of it. White hat hackers don’t deliberately destroy or steal data that belongs to others. Instead, they usually notify the system’s owner to the vulnerability before someone else has a chance to exploit the weakness.
The level of whiteness in a video signal.
Refers to wireless hacking. Hackers target vulnerable devices such as PDAs, wireless phones, and others.
Help available from an OS (operating system) program at the request of the user.
There are three types of code (a system of symbols presented in a manner a computer can understand): source code, object code, and machine code. In the before, during, and after of programming, source code is the before. Programmers design programs using source code. They then run the source code through something called a compiler. Although programmers can usually read and manipulate object code, nonprogrammers typically cannot read or understand object code or, in many instances, source code. The compiler creates object modules. All the different modules are then linked together or assembled to execute a program or function.
The intermediary code that’s been compiled is the object code, or the “during” of software programming. This code may or may not be the same as the final stage of code, the machine code. Computers cannot read high-level language (language generally intelligible to humans) or source code, and frequently, computers can’t read object code either. A link editor takes the object code and translates it into low-level language, or machine code, which then runs the program or function.
The foundational material of a hard disk platter, tape, flexible magnetic disk, or optical disc. For example, a hard disk’s substrate may be aluminum or glass, while a diskette’s substrate may be plastic such as polyethylene terepthalate. Manufacturers apply appropriate data storage coatings to the substrate to make a usable medium.
A programming language that uses call-by-value function calls, which evaluate their arguments before entering the body of the function.
A secret-key (symmetric) encryption algorithm that typically works on a single bit of a message’s data at a time. In the most common type of stream cipher, a key (comprised of a stream of bits) is generated without regard to the data being encrypted. The key, or keystream, is then combined with the data to encrypt it. There are many types of stream ciphers, and they are generally considered fast forms of encryption. A stream cipher with a randomly generated keystream forms the basis of the popularized “one-time pad" or Vernam cipher, which despite its impracticality offers an extremely high level of security.
A process developed by IBM and announced in June 2001 whereby a microchip's silicon is stretched so that the atoms that make up the silicon are aligned. This results in silicon with rows of aligned atoms, which lets electrons flow at speeds up to 70% faster than nonstretched (or nonstrained) silicon. This, in turn, enables the microchips that use strained silicon to operate up to 35% faster than ordinary microchips.
Short for keystroke, or the act of pressing a key on a keyboard to enter data into a computer.
A sleeve is a protective shell for your mobile device. Slimmer than a typical laptop bag, a sleeve gives your tablet or laptop basic protection against day-to-day bumps and scratches. This sort of case is handy for users who bring a laptop from one meeting to another, as it offers protection without the bulk of a standard case.
A picture of the contents of a monitor's screen. Press the PRINT SCREEN key to take a screen shot. Next open an image-editing application (such as Microsoft Paint, which comes with Windows) and then paste the contents of the Windows clipboard onto the canvas (press CTRL-V). Your screen shot will appear.
For as long as we’ve had office software, sharing digital document files (among users who have different types of office software) has been problematic. If a colleague creates a document with one brand of office software, you might find that important formatting is lost when you open it in your (different) office software. In fact, it might not open at all. To improve widespread (and long-term support) for digital documents, the Open Document Format Alliance created an open-source document standard. The format is supported by many popular office suites, including modern versions of Corel WordPerfect Office, Google Docs, OpenOffice.org, and Microsoft Office. To save a document as an ODF document, click Save As and look for the ODT (text), ODS (spreadsheet), or related extension.
Wherever you find a fan on your computer case, you are also likely to find a fan grille (sometimes referred to as a fan grill). Not to be mistaken for a fan filter (which blocks dust from being sucked into your system), a fan grille prevents curious children and pets from touching the rotating fan blade. Business PCs typically have nondescript grilles, while gaming PCs often have grilles in eye-catching shapes.
The definitions for "cloud" and "cloud computing" are still evolving and subject to debate, but you’ll find that many people are referring to online services when they say something is "in the cloud." Such services include online photo-editing services, Web-based email services, online storage services, and more. Businesses often think of cloud computing in terms of scalability: Internet-based services that can scale to meet the changing usage needs of a growing business. SaaS (Software as a Service), for example, is software that his hosted online (instead of being installed to your computers). It can be scaled for use by your growing company.
Yet another example of the real world catching up with science fiction, augmented reality describes technology that provides up-to-date information about the world around you. An augmented reality app on your smartphone, for example, may display information about a monument when you aim the phone’s camera at the monument.
A feature in word processors by which a word or phrase has a line or lines drawn through it, indicating that the word or phrase should be ignored or deleted.
An LCD (liquid-crystal display) distortion in which a dark area abutts a light area, and the border between the two shades becomes discolored instead of maintaining a sharp delineation.
A static link is a constant link. A static link is the opposite of a dynamic link.
A diskette that contains the necessary part of the operating system so the computer can boot up. Most computers with hard drives boot from that, but older computers might boot from diskettes in the A: or B: drive. It is a good idea to keep a bootable diskette handy in case something goes wrong with the hard drive, as most computers first check the diskette drives for bootable diskettes before checking the hard drive. A faulty hard drive can be bypassed this way.
Some search engines automatically “stem” keywords you use to search. For example, if you type “heads,” the engine actually only looks for “head,” ostensibly to find more matches. This is an uncommon practice and can sometimes be avoided by putting quotation marks around the keyword.
A Web site that offers incentives for visitors to stay awhile. For example, a Web site with stock quotes, glossaries, or other such features deters users from leaving the site to find other information. Sticky sites have more opportunities to show more advertisements or other site material to visitors than nonsticky sites.
A term used to describe the amount of time a user stays on a Web site. Popular Web sites have a high level of stickiness.
Often used in addition to polymorphic techniques to enable a virus to hide within a computer’s OS (operating system) and remain undetected by antivirus software. By intercepting routines used by an OS to find infected files and documents, the stealth virus then inserts some of its code into uninfected data, tricking the computer into recognizing the file as the original, unmodified version.
A term for software hidden in some free applications. Some retail sites, such as Amazon.com, let affiliates collect orders for them. The affiliates are then given a cut of the sales placed through them. Stealware places a specific affiliate ID on orders from Web sites that use affiliates. If you order through an affiliate, the affiliate's ID is replaced by the stealware, thus “stealing” money from the affiliate. Stealware can remain on a system even after you remove the software that was originally bundled with the stealware.
An individual set of parameters and profiles designed for one user of a multiuser system, such as for each family member using a home PC. It often consists of information about the user, such as the user's name and the password required to access the system, in addition to information about which files and programs the individual can use.
A tool found in many image-editing programs that helps you sharpen the edges of certain colors. When scanning images, this feature usually helps to improve the image’s quality.
A hidden command in a document that will not be printed when the document is sent to the printer, because it usually represents formatting commands that tell the program to perform functions such as return and indent. Examples of these characters include the TAB, ENTER, ALT, and CTRL keys.
The cache controller in L2 cache memory receives fetch (read) requests from the CPU, looks up the appropriate cache lines in the cache’s tag RAM, and tells the cache’s data store to send the lines of data to the CPU.
A board inside the computer that provides quick storage. Some computers have built-in cache cards; others have slots where a cache card can be installed.
The cache memory areas on and near your microprocessor are a vital component for giving the microprocessor improved speed and performance. The cache (pronounced "cash") provides high-speed, temporary data storage areas the microprocessor can access quickly. You can think of the cache area as a high-speed memory subsystem for your computer.
Cache memory areas are able to improve the performance speed of a microprocessor through four means. First, the cache memory consists of memory technology that works more quickly than the traditional RAM in your computer; it's also far more expensive. (Cache memory typically consists of SRAM [static RAM] versus the DRAM [dynamic RAM] usually used as the computer's main RAM.) Second, the cache memory areas are much closer to the microprocessor than traditional RAM, meaning they can deliver the data more quickly. Third, most cache areas run at nearly the same clock speed as the microprocessor, letting them work more closely in tandem. RAM runs at a much slower clock speed than the microprocessor. Finally, because the microprocessor typically only uses a small portion of a program or a data file at a time, storing the commonly used portion in cache is useful, even if the original program or data file is far too large to fit entirely in cache.
Today's microprocessors make use of two cache areas: L1 (level 1) and L2 (level 2). L1 cache is also known as on-die cache, on-chip cache, and primary cache. L1 cache usually sits directly on the microprocessor and is a smaller memory area than L2 cache. L1 cache is the first area the microprocessor checks when looking for data stored in memory. The L2 cache usually resides on the motherboard, although some manufacturers include L2 cache as part of the microprocessor's packaging or on the microprocessor itself, and is the second area the microprocessor checks for data stored in memory. To improve the performance of the L2 cache, microprocessor manufacturers a few years ago began connecting the microprocessor and the L2 cache with a backside bus. The microprocessor checks both cache areas before checking RAM. When the microprocessor finds the data it wants in the cache areas, it's called a cache hit. If the cache doesn't have the needed data, it's called a cache miss. As the microprocessor's data needs change, it updates the data it stores in the L1 and L2 caches, overwriting the oldest data in the caches.
In newer microprocessors, such as the Pentium 4 from Intel, the microprocessor uses prediction technology to determine the best sets of data to place in the L1 and L2 caches. This prediction technology is important to overall performance because it increases cache hits and minimizes the amount of time the microprocessor must wait for memory searches.
Cache memory first appeared in a computer—the IBM System/360 Model 85—in 1968. Nearly every PC built since then has included some type of cache memory. The Intel 468DX microprocessor, which Intel introduced in 1989, featured L1 cache on the chip for the first time, but it only had 8KB of cache memory. Off-chip L2 cache areas appeared soon after with 486DX4 and Pentium microprocessor chips from Intel in the early 1990s. Intel's Pentium II microprocessor, introduced in 1997, was part of an SEC (Single Edge Contact) Cartridge that included a high-speed cache memory chip. Today's microprocessors usually have 128KB or more of L1 cache memory and 256KB or more of L2 cache memory.
Because of the expense of cache memory, some low-price computers from a few years ago might be missing the L2 cache on the motherboard or microprocessor. Intel's initial Celeron processor, for example, didn't include L2 cache. However, as microprocessor components have continued to shrink and memory components have continued to be less expensive, almost all recent and current microprocessors contain L2 cache. With microprocessor components continuing to shrink, nearly all future microprocessors probably will contain an on-chip L2 cache. Newer Athlon microprocessors from AMD (Advanced Micro Devices), for example, include the L2 cache on the chip, improving its performance by about 300%. Some industry analysts think that as on-chip L2 caches become commonplace, computer manufacturers will begin including an L3 cache on the motherboard.
Terms associated with cache:
cache buffer: A cache buffer is the area of RAM (usually 2MB or less in a PC) that exists within nearly all newer hard drives, CD-RW (CD-rewriteable) drives, and DVD-ROM drives, giving the microprocessor faster access to data that's normally in permanent storage. The cache buffer usually maintains a copy of the latest data the microprocessor retrieved from permanent storage. In most newer printers, manufacturers have included cache buffers, which hold data waiting to be printed. A similar process, called disk caching, reserves a portion of RAM to mirror the last data from the hard drive, giving the microprocessor faster access to the data if it's needed again.
Web browser cache:
Cache also refers to the portion of memory and the computer's hard disk that Web browsers use to store temporary Internet files, usually called the Web browser cache. Using a portion of the computer's resources to store Internet files, especially graphical images, lets the Web browser display Web pages more quickly than it could by downloading the graphics from the Internet. Using a cache area makes sense in this instance because the graphics on a Web page rarely change.
ISPs (Internet service providers) and Internet content providers also make use of cache servers (sometimes called cache appliances), which are specialized computers that store copies of commonly accessed Web pages. Cache servers usually use software to measure the most popular Web pages and then download those pages to the cache server during nonpeak Internet usage times. The cache servers then check back with the originating Web server from time to time to look for changes and updates. Cache servers are located throughout the world, and they help speed downloading of Web pages by two methods. First, they alleviate traffic on the server where the commonly accessed Web page resides, giving the server better overall performance. Second, because chances are good one of the cache servers is physically closer to your computer than the originating server is, the Web page has a shorter distance to travel to your computer and can arrive faster.
A map of the cables that connect components to a computer system. The map shows how each component is connected to the computer.
A device that divides the signals intended for the cable modem and the television. If your home is equipped with a cable modem, when data from a cable company arrives at your home using a coaxial cable, it passes through a splitter.
A category of cable organization products, such as split-loom tubing and heat shrink, that help keep cables neat and improve airflow inside the PC case.
Used when installing a PnP (Plug and Play) ATA/IDE (Integrated Drive Electronics) hard drive so that the computer automatically configures the drive as either master or slave.
When followed by a colon, C refers to the C: drive, usually the hard drive inside a computer. However, this designation can be changed by the user.
The area of a cable station where the satellite dishes and antennae that receive the video programming for the cable network are located. It also houses the routers that connect the feeder lines from the cable modems to the Internet.
A Microsoft archive format used for distributing Microsoft software. Distinguishable by its .CAB file extension, a CAB file contains one or more compressed files in a single file. Large files sometimes span from one CAB file to another.
Software that aids programmers as they develop other software. Such software can help in different phases of development, such as debugging, linking, editing, or others.
To be temporary or capable of change. For example, software gets its name from the idea that changes can be made by altering the programming code. By contrast, hardware is a physical contraption that can be added to or broken but cannot be changed. Also refers to a digital image that lacks definition and crispness. An image is said to be soft when it appears blurry or unfocused.
A record of the state of a system at a particular moment. Also can mean screen shot.
Text is data that a computer stores, and it is represented as words, sentences, paragraphs, and punctuation.
Terms associated with text:
text cursor: An on-screen indicator that marks a specific location within text. When typing text, the cursor marks the location where the next character typed will be placed. When editing existing text, the cursor is used along with the mouse or certain keyboard keys to select text for manipulation. Once text is selected, you can replace, delete, cut, or copy it, or you can change its attributes, such as the style of font. The cursor is moved to different locations using the mouse or directional arrow keys on a keyboard.
text editor: A program that lets a user input text and save the text as a file. Notepad, a standard Windows component, is an example of a text editor. Although programs, such as WordPerfect or Word, let a user edit text, they are generally referred to as word processing programs. The difference lies in the capability for advanced manipulation of text that is found in word processing programs but generally not in a text editor. Text editors tend to be basic programs that let a user enter and edit generic text, but they are not capable of performing a wide range of special formatting.
text flow: The spanning of one body of text across more than one text placeholder. In desktop publishing programs, documents may contain more than one text box, which is a defined region into which text is inserted. The automatic flow of text is something that you can turn on or off within the preferences of these programs. When automatic flow is enabled, if one text box becomes full without holding all of the entered text, the excess text will automatically be placed into the next text box.
text mode: A display mode in which a computer monitor displays only text characters and no graphics. This was the primary type of interface in the days of DOS.
text-only: A mode in which only text is displayed, without graphics. Some Web sites provide a text-only version that loads much faster than the graphics-based version.
text-to-speech: The technology of converting written text into audible words and sentences.
text wrap: A feature found in text editors and word processing programs that automatically starts a new line of text when the right edge of the text area or window has been reached.
Netbooks are tiny, laptop-like devices that owe their popularity to their portability. Because they are so small (and have built-in Wi-Fi), they make good companions for travelers who want to surf the Web. That portability can come at a performance price: some netbooks don’t have the power to rival traditional laptops.
E-readers, which are often referred to as ebook readers, are devices designed for displaying books. Examples of popular e-readers include the Amazon Kindle and Barnes & Noble NOOK. Many devices that are not designed specifically for digital books (such as PCs, smartphones, and tablets) can also display books (once ebook reader software is installed).
Social networks, such as Facebook, have given this term an additional meeting and even turned it into a verb. In social networks, friends are contacts; to friend someone is to add them to your list of contacts in the network.
Microsoft’s latest search engine has gained popularity by providing helpful search results and intriguing users with its main page picture, which changes daily. Run your cursor over the image and you’ll see links that you can click to learn more about the image subject. Bing is a rival to Google.
The maximum rate at which a system can transmit data over network lines. This rate is measured in bps (bits per second). Most current networks use 100Mbps (megabits per second) network cable.
Traditionally a centralized computer system that gives access to more than one person at a time, such as a mainframe. It is also used to describe software several people can access at once.
A control mechanism that lets two or more computers share a single peripheral, such as a printer, a scanner, or a monitor. With an A-B box in use, the user can decide which computer is able to use the device at any one time by turning a switch.
Short for motherboard, the circuit board that provides the foundation of a computer.
A shortened version of the word "modification." For example, a case mod is a modification made to a computer case. One popular example of a mod is a window cut into a side of a computer case to show the insides.
The interference problem caused by the many routes information takes in a wireless transmission. An RF (radio frequency) wireless network transmission, for example, might bounce off of various objects as well as strike the receiver directly, resulting in a jumble of signals of varying and sometimes conflicting properties such as phase differences. The receiver’s job is to sort out the problems caused by multipath and winnow out the best example of the transmission.for example, across a network.
A manufacturer of 12-volt, four pin connectors. The connectors allow your PC’s power supply to connect to other components. Computer enthusiasts often refer to these connectors as “Molex connectors.”
Morphing is an image transition effect used in graphics programs that is constructed by image sequencing between two or more images. In other words, the image in frame 1 is altered slightly in frame 2, then again in frame 3, and so on until the image has morphed, or experienced a metamorphosis, into another different image. For example, in a simple morph, animators may begin with an image of a sphere, and then through a series of frames, the sphere changes into a face. The transition between a man and a werewolf is another, more complicated example that may visually illustrate the effect more dramatically.
Morphing is used in video, graphics, and film and includes 2D and 3D morphs. For images generated from 3D models, 3D morphing can create intermediate 3D models directly from the original. The morphs are then rendered to produce an image sequence that depicts the transformation. In 2D morphing, a new morph must be recomputed every time the viewpoint or illumination of the 3D model is altered because the 2D techniques lack information on the model’s spatial configuration, so changes in illumination and visibility are impossible to control. For example, when a 3D object is morphed in 2D, features not visible in the original 2D image, such as a model opening her mouth, would display as thicker lips instead of showing her teeth. Not only are 3D morphs more realistic, but they are also easier to create.
Morphing is a popular transition effect used in films today, and animators are often awarded the Technical Achievement Award from the Academy of Motion Picture Arts and Sciences for excellence in this field.
Multicast is a one-to-many or multiple-to-many broadcast over the Internet where one or multiple sources send transmissions to multiple receivers; for example, corporate messages to employees, video- and audioconferencing for remote meetings and telecommuting, stock quotes to brokers, and the replication of databases and Web site information. With multicast, source providers can send a single copy of a message to multiple recipients, but only to those individuals who want to receive the information.
Receivers, or listeners, join specific multicast session groups as subscribers, and then only those individuals receive the multicast sessions that are broadcast to the members of that group. Senders are not required to maintain a list of the members because the members sign up for the multicast broadcasts they want to receive. Only one copy of a specific multicast broadcast passes over any link in the network, so copies of the broadcast are made only where paths diverge at a router.
As opposed to unicast broadcasts, which require each listener to make a separate connection to the source server (requires the source to send an individual copy of a broadcast to each requester, also known as point-to-point unicast), multicast sends one message, one time, to many listeners. Unicast receivers are limited by the bandwidth available to the sender, plus unicast causes a tremendous load on the source server, which results in major congestion across expensive WAN (wide-area network) links as the number of listeners increase.
For concerts and entertainment, lectures and educational seminars, and even board meetings, multicast broadcasts are the answer for one transmission source; a university, for example, can broadcast a professor’s lecture to an entire classroom of registered students. Only the students who sign up for the course will receive the multicast lecture, and the source computer at the university only has to make one connection and send one broadcast.
Analysts predict all of television and radio will eventually be delivered primarily over the Internet, and multicast is designed specifically for this function. Hundreds of radio stations already provide multicast sessions of their local broadcasts to the Internet population, and local television station broadcasts are on the horizon. Very soon, you won’t need cable to watch a program in Japan or listen to an underground radio station broadcasting from Russia. Multicast has the potential to expand the Internet beyond email, e-commerce, and billboard sites to global broadcast communications that will offer a true audiovisual window to the world.
Aligned with the right margin, side of a page, or side of a screen.
A measurement concerning the read/write heads in hard drives. Flying height describes how far from the disk surface a head flies while the drive is in use. The heads would normally rest upon the disk surface, but the disk’s spinning motion creates wind which buoys the aerodynamic head mountings (called sliders) like the wings of an airplane. The heads in modern hard drives fly about three millionths of an inch above the disks. Platter rotation speeds are matched to slider designs to produce a desired flying height. Flying height is a frontier in hard drive technology, as lower heights allow denser data. Manufacturers facilitate lower flying heights through smoother disk surfaces and alternative disk materials.
Aligned with the left margin, side of a page, or side of a screen.
A technique used by video cards to help create an illusion of depth. By using this method, objects can be made to gradually appear in the foreground from the background, rather than having an object suddenly pop into view in the horizon.
A short message (no more than 140 characters) on microblogging service Twitter. When you send a tweet, it is available to the public and anyone who has signed up to receive your tweets (known as "following"), depending on the security settings you choose in your account profile.
A daemon (pronounced da’mon or de’mon) is a memory resident computer program that runs in the background, typically without user interaction. Daemons are often started automatically at bootup in a process referred to as spawning. They respond to specific events or triggers to perform predefined tasks.
An example from the UNIX OS (operating system) is the spooling daemon. When an application writes a file to the LPT (line printer terminal) spooler’s directory, the spooling daemon is automatically invoked to print the file. The application wanting the file printed does not need to worry about resource competition or the complexities of LPT spooler. It simply drops the file in the directory and assumes the daemon will complete the task.
Non-UNIX OSes also use daemons, but they are usually known by a different name. Windows, for example, refers to these types of programs as System Agents (Windows 9x/Me) or services (Windows NT/2000/XP).
The term daemon is often used interchangeably with demon, especially in the UNIX world, where daemon is considered mildly archaic. In some circles, a slight distinction is made between the two, where daemons are part of the OS and demons are part of an application or program. In this context, a trigger in a DBMS (database management system) is considered a demon because it is part of the DBMS, not the OS.
The term daemon originates from Greek mythology, in which daemons were guardian spirits.
Appearing first in Microsoft Office 2007 programs, the Ribbon is a large menu that replaces the toolbars found in previous versions. The Ribbon groups icons for commonly used features, rather than storing them in drop-down menus. Although switching from the toolbars (of older Office programs) to the Ribbon can take some getting used to, many users have grown to prefer the Ribbon. In turn, other software publishers have incorporated Ribbon-like menus into the interfaces of their software.
Microblogging is a version of blogging in which posts are restricted in length. Twitter, for example, limits its messages (known as "tweets") to 140 characters. Microblogs are often used to make announcements and brief comments; blogs are better suited to detailed posts.
In forums and social networks, an avatar is usually a square image (an illustration or photo) that represents the person posting the message. Also referred to as profile pictures, avatars often have much smaller file sizes than today’s digital photos. Although your social network or forum will have instructions for resizing your photo, cropping the image to 180 x 180 pixels usually does the trick. "Avatar" also refers to your character in video games and other online worlds.
The paramount wavelength of a color. A shade of color combined with the brightness, contrast, and sharpness of a graphical, photographic, or virtual reality image.
Besides getting rid of the dust and debris that have accumulated on the surface of a computer and its peripherals, housekeeping also can mean optimizing the hard drive, getting rid of old or unused files, or making sure the system clock is running on time. Also a set of directions executed at the beginning of a program.
One of Microsoft’s bug fixes that replaces some current files with revised files in an application.
The open directory in which a user currently is working. When commands are executed within a directory that will affect that directory or its files, the commands can be typed without a path name. Also called the working directory.
A temporary method of bypassing bugs or inoperable features of software. Workarounds, not to be confused with a fix (which resolves a programming problem in a program), can themselves often be ineffective, time consuming, or otherwise problematic. Whenever possible, a vendor will issue a workaround to accommodate users until they have completed a solution to a problem that requires programming changes.
A means of preventing users from editing files or saving files to a storage medium. Information can be write-protected in at least three ways. Through an operating system's file management features, users can activate a read-only attribute on files by using a command such as MS-DOS' ATTRIB. On networks, sharing software can establish security settings that provide write access to some users but not others. Lastly, diskettes have fairly unsophisticated write-protect mechanisms. On a 5.25-inch diskette a square notch is carved out of the side of the diskette (probably next to the label); covering the notch with tape restricts users to read-only access. A 3.5-inch diskette has a square hole in the upper corner of the diskette (again, probably near the label). A tab slides over the hole to lock the diskette, sliding it away from the hole restores write access.
A pathname in relation to the root directory.
Using a serial cable and serial port to transfer data from one device to another.
A data structure which represents a virtual 3D environment, such as that used by developers under the Fahrenheit architecture. A scene graph contains the information for every object in the 3D environment, including its location, colors, transparency level, lighting, etc. It is organized spatially to help the developer keep track of object locations while programming. A scene graph is continually and automatically updated when the application is running to keep it current in light of moving objects in the 3D environment, such as the lead character in a game.
Although scanners were first used to import graphics for desktop publishing, since their introduction, scanners have become common office equipment. They are commonly used for desktop publishing, copying, electronic document distribution, and faxing.
In the past, scanners were specialized machines that required users to have expert knowledge to use them. Nowadays, scanning is simple. No longer do users need to understand such concepts as bit depth and ppi (pixels per inch). Instead, special software lets users get good results with little technical knowledge.
Some of the first scanners designed for home use were the ScanJet series of scanners that HP manufactured. You can use the ScanJet series to create greeting cards or store family documents, and students can even create reports for school assignments. HP’s ScanJet 5400cxi scanner, for example, has new CCD (charge-coupled device) scanning technology for 2,400dpi (dots per inch) photo-quality resolution and fast, 8-second preview scans.
Sawfish is a window manager for the Linux platform. As a window manager, sawfish draws and manages windows only. Other functions, such as configuring background images and creating application panels and docks are left to other applications. Sawfish, formerly known as sawmill, is commonly used in conjunction with GNOME.
A computer that is on a distant communications link to a more powerful system.
A computer expert hired to attempt to break into a computer network, thus helping a company spot its own weaknesses to illegal hacking.
Safe Mode is a Windows troubleshooting tool that lets computer users access Microsoft Windows using only the computer’s most basic drivers. For example, in Safe Mode of Windows 2000, the default settings (which is a VGA [Video Graphics Array] monitor, Microsoft mouse driver, no network connections, and the minimum device drivers required to start Windows) are used. You cannot access CD-ROM drives, printers, or other devices while in Safe Mode.
An example of a situation in which you will want to get into Safe Mode is if your computer won’t start after installing new software. To enter Safe Mode, click Start, Shut Down, and then choose Restart. Next, press and hold the CTRL key until the Startup Menu appears. On some OSes (operating systems), you will need to hold down the F8 key instead of the CTRL key. Next, enter the menu choice number for Safe Mode and press ENTER. When using Windows XP, restart the computer and press the F8 key. When the Windows Advanced Options menu appears, select an option and press ENTER. When the Boot menu appears again with the words Safe Mode displayed at the bottom, select the installation that you want to start and press ENTER. Once in Safe Mode, you can change computer settings or remove the software that caused the problem. If the problem does not reappear after starting in Safe Mode, you know the problem is not with the default settings or minimal device drivers.
If a new device or driver is causing a problem, start Windows in Safe Mode and reconfigure the settings or remove the device. Use Device Manager to check for any hardware conflicts. To use Device Manager, click Start, select Settings, click Control Panel, and double-click System. Next, click the Device Manager tab in the System Properties box. In WinXP, while in Safe Mode, choose the Last Known Good Configuration option. This option starts Windows using a previous good configuration. Safe Mode will not solve any problems caused by corrupted or missing drivers or files.
A menu of choices will appear on your screen after you are in Safe Mode. The most common Safe Mode options are:
Safe Mode: This starts Windows using basic files and drivers, including mouse, monitor, keyboard, storage, video, and default system services.
Safe Mode with Networking: This option starts Windows using basic files and drivers, as well as network connections.
Safe Mode with Command Prompt: Starts Windows using basic files and drivers. After logging on, the computer displays the command prompt instead of the Windows Desktop.
Enable VGA Mode: Starts Windows using a basic VGA (Video Graphics Array) driver. If you have installed a new driver for your video card and Windows is not starting properly, this is probably the most useful mode.
Last Known Good Configuration: Starts Windows using the Registry information that was saved the last time you shut down your system. If you choose this mode, you will lose any changes made since your last successful startup.
A useful and noteworthy aspect of hardware or software is called a feature. For example, a common feature of a word processing program might be that it performs spelling and grammar checks concurrent with the actual composition of a written document. A feature of a notebook computer might be that it runs for six hours on batteries. And an example of a feature of an OS (operating system) could be that it has a built-in Web browser.
Generally, a feature is an intended, documented, and advantageous facet of a computer system. On the other hand, an unintended, undocumented, and disadvantageous aspect of a computer product, such as a program, is called a bug.
An instance of where even good features can turn bad involves the inevitable computer trade-off between an abundance of useful features and a welter of confusing complexities. There reaches a point in program development where the accumulation of more and more features is no longer helpful. Instead, it is counterproductive, resulting in long hours of learning an application or avoiding the use of the complicated application altogether. This condition of an oversupply of features is termed featuritis or feature creep. Feature creep can occur across a series of developing versions of a system or application or in the course of the development of a single application at a particular time. Often the latter case of feature creep will happen because customers or the developers’ supervisors become increasingly and perhaps unconsciously ambitious about a product’s final capabilities and goals.
The name given to a custom icon used for a specific Web site. A Web site can create a 16 x 16 pixel icon that can be named favicon. When a user adds a Web page, Internet Explorer version 5.0 or newer checks for the presence of a favicon.ico file. If the file exists, the favicon is displayed next to the name of the Web page in a user's Favorites list.
Allows a computer to suffer some types of faults without losing data. Operating systems, such as Windows, have some of these capabilities built into their architecture. However, they do not always work.
A malfunction. Most often refers to glitches in a network system but also can refer to individual computers.
Also called bloatware, fatware is software that's inefficient because it takes up a great deal of hard drive space and/or system resources.
In a client/server environment, a fat client does most of its own processing, leaving little or no work for the server.
A version of software that consumes a lot of system resources. This is often the version that runs on the widest range of computers and operating systems; system-specific versions are much more efficient.
A modem protocol feature that lets two modems speed up when transmission improves; it comes into play after using a fall back to compensate for error-ridden transmission.
A method of determining the reliability of a device, typically a hard drive. For instance, a failure rate of 300,000 hours means one failure occured for every 300,000 hours of testing.
The window of time in which a system failure is expected.
A situation in which a computer cannot continue to perform as designed. Failures are caused by power fluctuations, misuse, poorly manufactured or designed hardware or software, and other calamities.
This term refers to the automatic activation of a backup system in case of a failure or the need to repair a server, database, network, or other computer system. The failover backup system is a redundant, or duplicate, system that picks up where the primary system leaves off. This means its deployment is transparent to users. The computing tasks are seamlessly offloaded to this secondary system, which is sometimes called a hot standby or a warm standby.
For a PC, a failover could be a second processor that takes over in case the first processor fails. In a network, a failover can exist for any number of components; for example, it is common for large network systems to employ redundant hard drive arrays. An uninterruptible power supply is another type of failover component.
Particularly vulnerable in networks are the connection paths—the communication lines connecting two points (nodes) on a network. If any one component along the path fails, all traffic along the path stops, disrupting the entire network. Modern networks can have failover connection paths, so if one route to the processor is down, the data can travel an alternate route.
Having a failover is especially important for mission-critical systems, such as credit card processing systems, which are accessed constantly. Computer systems with built-in failover are said to have a very high fault tolerance and are quite expensive.
A computer system designed to shut down nonessential components in the event of a failure but keep alive important functions, such as protecting against a loss of data, as long as possible or until the problem is repaired. Also soft fail system.
Face recognition is the biometric technique of identifying individuals by facial features. Face recognition is a type of biometric analysis, which aims to identify people by using biological or anatomical human characteristics, such as fingerprints and handprints, iris patterns, voice patterns, and facial structure.
More specifically, face recognition employs digital video cameras and software to capture an image, isolate a human face, and extract specific features of the face that do not change. Such features may be upper sections of the eye sockets, the area around the cheekbones, and the sides of the mouth. The individual’s features are then compared to other feature-sets in a database of photographs.
Face-recognition technology works with off-the-shelf PCs and video cameras, making this identification technology relatively inexpensive to install and operate. High-resolution images provide even better matches.
There are four basic methods employed in face-recognition software: eigenface, feature analysis, neural network, and automatic face processing. Eigenface, which means “one’s own face,” employs 2-D grayscale images that represent distinctive features. MIT (Massachusetts Institute of Technology) patented this technology. Feature analysis is similar to Eigenface, but can better accommodate changes in facial movements, such as smiles and frowns. Neural network technology uses both the newly scanned face and the stored face to determine if there is a match. An algorithm looks at the similarity of unique features. Lastly, automatic face processing uses distances and distance ratios between obvious features such as eyes, the end of the nose, and corners of the mouth.
Although it is an ideal application for security, the use of face recognition for public security is a controversial one. One of the initial deployments of facial-recognition technology in the United States was at the 2001 Super Bowl where police in Tampa, Fla., used it to scan faces in the crowd to search for known terrorist suspects. This sparked a major debate about governmental police powers and citizen privacy.
In the private sector, companies use face recognition to limit employee access to sensitive data. An example is hospitals that limit access to their patient records to physicians. As for governmental use, some states are using the face-recognition technology to prevent identity theft. In these states, the DMV (Department of Motor Vehicles) is scanning an applicant’s old driver’s license and comparing it with his new photo.
Face-recognition technology advocates say it is an excellent biometric solution for airport security because it can identify individuals without interaction. Enthusiasts also tout the technology as a way to authenticate ATM (automated teller machine) interactions or voting procedures, and to screen potential government and school employees.
But civil rights advocates, such as the ACLU (American Civil Liberties Union), worry that out-of-date photos and bad lighting could result in numerous misidentifications, or false-positives, when individuals are incorrectly matched with photos of other people. Indeed, one of the privacy advocates’ arguments is that face-recognition software doesn’t work as advertised, and it is easily fooled by changes in hairstyle, facial hair, aging, weight gain or loss, or simple disguises. Of course, the privacy advocates are highly concerned that “face prints” collected by the government will be misused.
Whether face-recognition technology will be widely implemented in public places in the United States depends a great deal on how face-recognition applications balance public security with personal privacy. The nation’s courts will ultimately decide the issue.
Fab refers to a manufacturing plant where various types of semiconductor chips, or microprocessors, are fabricated for production or part of product development. Fab facilities are highly specialized and notoriously very expensive to build, costing several billion dollars.
A key element of any chip fabrication plant is the clean room, the factory floor where chips are made. A clean room is more sterile than a hospital operating room and must be as dust-free as possible. Even the tiniest speck of dust can wreak havoc on a chip, much like a boulder crashing onto a freeway interchange, ruining many or most of the millions of microscopic transistors on the microprocessor. The air in a clean room is completely replaced several times per minute. The most sterile, or class one, clean room has no more than one particle of dust per square foot. Fab clean room workers must wear super-clean antistatic outfits called bunny suits to protect the chips they work on from skin flakes, hair, and other human particles.
In a fab clean room, microprocessors are built by creating very thin layers of silicon dioxide and polysilicon on a base wafer of silicon. This is achieved by exposing the wafer to various chemicals, gases, heat, and light. One common chip-building technique is called masking; a substance called photo resist, which functions like a stencil, protects areas of the chip, while the exposed areas are etched with patterns by acids. These etched areas of the chip may be bombarded with ions to alter electrical conduction and then layered with metal atoms, which serve as the electrical connections in the chip.
It takes about 20 connected layers and more than 250 steps to complete the process, depending on the design of the microprocessor. The chip layers are about 10 nanometers thick and must be positioned accurately within one-tenth of a micron. It may take as long as 12 weeks to complete a whole set of chips on a wafer of silicon, as it travels throughout the fab on an assembly line, where it’s treated, layer by layer, at various stations.
Each wafer contains hundreds of identical microprocessors. The microscopic circuits in each chip are individually tested, and the wafer is sliced into separate chips with a diamond saw. At last, the chips are packaged for connection in all kinds of devices, many of them everyday items, such as toys, calculators, and fire alarms.
A sub fab is an annex of the chip fabrication plant that supports all the machinery required to build the chips. It contains generators; the plumbing, filtering, and vacuum systems; tanks of etching acid; as well as the equipment that monitors clean room particulates. The sub fab is also an ultra-clean environment.
Large companies, such as Intel, build and operate fabs around the world. Some chip manufacturers sell the use of their manufacturing facilities; some build chips exclusively for other companies.
A fabless microprocessor company is one that does not have a manufacturing plant. Such vendors may design and test chips, but they must rely on another company with fab facilities to actually build their chips.
The area of a cable company that houses the satellite dishes and antennae that receive the video programming for the cable network. The head end of an online service is the company's computer system and the databases.
When an electronic device (such as a microprocessor) emits energy (heat) and a cooling device (such as a heat sink or fan) is in place to cool the electronic device, a heat leak is the amount of heat that escapes despite the cooling device's efforts. A heat leak is measured in energy lost from the cooling device, and in heat gained by the area surrounding the cooling device.
Monitoring devices connected to hardware circuits to oversee how the hardware works with the system or to indicate when a problem occurs.
Hardware keys act as security devices. Some computer systems, and some expensive software or peripherals, require users to insert a key before the hardware will run. If there is no key, there is no operation. Some computers have a key that plugs in the front or back of the system, while some programs or peripherals will install a special key box in the port. The peripheral or software will not work if the key is not inserted in this box because the box contains a required code or password for the device.
An easy-to-access table on a Web page that contains a series of hyperlinks that lets a user quickly and easily obtain information. The "View terms starting with..." option for this dictionary is an example of a hash table. By clicking a specific letter, a user is able to view dictionary terms beginning with that letter without having to navigate through the entire dictionary.
A location in a software's application where programming that invokes a certain function is inserted.
In statistics, a histogram is a kind of bar graph that shows how data is distributed. It comes from the Greek word histos, meaning “pole” or “mast,” and gram, meaning “chart” or “graph,” and it is sometimes also known as a pole chart. The horizontal axis, or y-axis, shows units, and the vertical axis, or x-axis, shows how often something occurs. You can switch this format, but it is not usual. The bars show measurements and frequencies of whatever is being measured. High bars would indicate a higher value and low bars indicate a lower value. This arrangement is helpful for showing not only the largest and smallest categories of data but also how they are distributed.
Histograms are used frequently in computing. Graphics programs, for example, use histograms to show how pixels are distributed in an image and therefore reveal the amount of detail in different areas of the image. In practical terms, this helps a graphic artist determine if she needs to clean up an area in shadows or if the highlights are too prominent in order to make a balanced image. This is sometimes called histogram equalization.
Histograms are also used in science and data gathering to represent grades and scores or weather patterns. Hardware and software performance is sometimes displayed in histograms.
A process used when bitmapping digital fonts. Hinting blurs the corners and curves of individual characters in a font so they appear as smooth as possible when displayed or printed in low resolution.
Refers to programs or software plug-ins that redirect you from one Web site to another. A plug-in from Gator.com is notorious for being hijackware, which is sometimes known as scumware.
A large area filled with many disk drives.
On a network, a remote disk drive accessible by some or all members of the network. Data can be written to and read from a disk server by members of the network.
The type of inkjet technology used in most computer inkjet printers today. Drop-on-demand describes exactly the process used: the printer’s driver software demands the printer fire a drop of ink onto the correct spot on the page, eventually forming text and images. Thermal inkjets and piezo-electric inkjets are both drop-on-demand printers.
A character that represents a frequently occurring number or value.
A data format is a way of organizing information in a computer file so specific computer programs and applications can access the data. Microsoft Word and Microsoft Excel, for example, store documents and worksheets in different formats due to the nature of the information these files typically contain.
The file name extension, the portion of the name following the period, found on a PC is often used to designate the data format. For example, Excel files usually have an .XLS extension, whereas Word files have a .DOC extension. The standardization of these file extensions lets the OS (operating system) know which application to launch when a user accesses a certain data file. For example, double-clicking somefile.xls, (where somefile is the file name), opens your file in Excel. If the file had been named somefile.doc, it would be opened in Word. It is up to the user or the application creating the file to assign the appropriate extension. Simply renaming a file created with Excel from somefile.xls to somefile.doc does not automatically convert it into a format readable by Word.
In addition to the file extensions mentioned above, other common file extensions and their data formats include: .CSV (comma separated variables), .DAT (binary data files), .EXE (executable file), .GIF (Graphics Interchange Format), .MDB (Microsoft Access), .PPT (Microsoft PowerPoint), .RTF (Rich Text Format), and .TXT (ASCII text files).
Many computer programs contain built-in filters that can read and/or write files stored in formats different from their native formats. It is common for vendors to include filters that let users read or import files from competitive products to encourage users to switch vendors.
The area of a hard drive or diskette that can store data and programs. When a disk is formatted, a boot record, partition table, root directory, and file-allocation table (FAT) are established first on a small portion of the disk. The larger remaining portion of the disk is considered the data area.
The horizontal wire that stabilizes and limits the vibration of the aperture grille on an aperture grille display. Its faint shadows may be visible on the screen. Larger monitors have two parallel damper wires, while smaller monitors have only one.
To make a window larger when using graphical interfaces. In many applications, a zoom box lets the user maximize a window, making it fill the entire screen. When the zoom box is selected again, the window returns to its original size. Also refers to magnifying a portion of a document on-screen in order to view it more closely.
Located inside a LAN (local-area network), zones are subsets of the larger network.
A Web server that is "hijacked" by a computer cracker to launch a DoS (denial of service) attack on another Web site. The cracker secretly places malicious code on the zombie Web server, and the zombie is instructed to launch the DoS attack at a later time.
To remove zeros from a number without affecting its value. The number 000.444, for example, could be written as .444.
A font composed of printers' symbols from the International Typeface Corp. that includes arrows, geometric shapes, stars, and circled numbers. It is a built-in font in PostScript laser printers and can be purchased in Type 1 or TrueType format for other printer types. The font's formal name is ITC Zapf Dingbats.
To set a variable or series of bits at zero.
Emulates the Unix Talk program, which allows users at different terminals to communicate with one another. YTalk, however, is capable of multiple simultaneous connections.
The largest measurement of computer storage, representing 1,208,925,819,614,629,174,706,176 bytes, or about 10 to the 24th power. Currently, the largest hard drives have storage up to one terabyte, which is about one trillion bytes.
This has also been known to as the Year 2000 Problem and the Millennium Bug. Headlines on national tabloids foretold the end of the world. Predictions of bank failure and global economic collapse were uttered. Advertisements sprouted for portable generators and survival supplies in anticipation of power generators everywhere grinding to a halt. Nuclear plants were set to melt down. And worst of all, your PC might not boot.
These predictions of catastrophe, almost enough to make biblical authors blush with humility, dominated public consciousness in 1998 and especially 1999. Reports emerged about how public utilities and world governments weren’t acting fast enough, and come 12 a.m. on Jan. 1, 2000—which, for the mathematically curious, was one year before the start of the third millennium A.D.—computers of all types and sizes the world over would fail because of one little problem.
The problem has its origins back in the early 1900s when data had to be stored on punch cards. The “19” digits in date fields seemed extraneous when those two characters spread over thousands of cards translated into a lot of extra work. By the 1960s and 1970s, a similar problem existed with programming mainframe computers, often using the COBOL (Common Business-Oriented Language) language. Each kilobyte of memory cost a considerable amount of money, the turn of the century was a long way off, and again year fields were chopped to two digits. This tradition of expediency was carried over all the way into the 1990s, permeating systems from supercomputers to the tiny chips built into traffic lights and elevators.
The problem was one of arithmetic. Boeing, which sometimes forecasts purchases as far as seven years in advance, first became aware of the issue in 1994. Imagine trying to plan orders for 1997, 1998, 1999, 1900, 1901. . . . With only two digits to go on, the system didn’t know that it was trying to plan operations for dates starting with “20.” The digits “19” were assumed as prefixes for all year fields. The system only knew that it was trying to compute a future event on a date that had mathematically already happened. In some cases, this conflict might be resolved by deleting the database record. (This might be a serious problem if the record in question is your Social Security account.) When credit cards started using year 2000 expiration dates, some stores reported that their entire card processing systems crashed.
To solve the problem, a global army of programmers set to work. Retired COBOL engineers were summoned back into action to fix antique code. Manufacturers devised plug-in cards for PCs that would trick motherboards into using the proper time. Operating systems needed patches. Spreadsheet programs in particular had to be methodically combed for two-digit year entries. In reality, though, most of the potential hazard for desktop PCs vanished if the user merely turned his machine off on New Year’s Eve, booted up the next morning, was careful to manually enter the BIOS (Basic Input/Output System) and change the year to 2000, then reboot.
Of course, there was no global catastrophe and the media were hard pressed to find examples of actual January 2000 Y2K glitches. There were a few, but nothing dramatic. In the end, the biggest problem for most people on New Year’s morning of 2000 was a mild hangover or a pile of dirty dishes in the sink.
A single cable that meanders into two sections and thus forms a Y shape, allowing you to hook up two devices, such as two joysticks, to be used simultaneously.
A listing of Web sites that often appear as links on a blog and are used to express connections between blogs. The list of links is used to relate the site owner's interest in or affiliation with other known bloggers. These lists can be made dynamic through services such as BlogRolling.
An encryption algorithm used in private-key (symmetric) encryption. A block cipher breaks a message into pieces and then encrypts each piece. Compare to stream cipher.
Refers to the process of copying a large array of bits from one part of the computer’s memory to another part, most often when the memory determines what’s showing on your screen.
Slang for a session or meeting in which a group of people try to assign blame for a recent failure.
To have text or graphics printed off the edge of a page. Bleeds often are used on purpose with graphics, but text bleeds can be a sign of a problem with a printer or the software's print setup.
A transmission of data in binary, or digital, form.
A portion of a hard drive or diskette that cannot be accessed for storage purposes. Both hard drives and diskettes use a round platter to store data on. Upon formatting, this platter is divided into sectors (extremely thin, pie-shaped wedges) and tracks (concentric circles, like rings on a tree). The sector and track location is recorded when data is stored on a drive or diskette. This enables the computer to reassemble the data when requested by the user. When a sector is not usable (data cannot be stored there), it is referred to as a bad sector. New drives and diskettes should be free of bad sectors, but media degrade over time, and a few bad sectors are not uncommon on older equipment. Several DOS and Windows utilities, including Check Disk and ScanDisk scan for, and either repair or mark, bad sectors. In addition, format utilities identify and mark bad sectors as unusable. A previously good sector can go bad through a failure of some sort. If this occurs, any data stored on that sector may be irretrievable. (Specialized software and/or retrieval services may be able to access it.) A drive which has numerous bad sectors, or on which the number of bad sectors is increasing, is a likely candidate for total failure.
Software that facilitates the creation and editing of a Web page by translating the HTML (Hypertext Markup Language). Also refers to a person who is in charge of maintaining a Web site.
The person who manipulates the look and feel of a Web site to make it more functional and intuitive. This person is responsible for most of the graphical elements on a page and also dictates where text-based content is placed.
A slang term for tiny images imbedded in some Web pages and HTML email that let organizations, such as advertising firms, track your movements on the Web. By establishing behavioral patterns such firms hope to better target their pitches and sell more products. The insidious nature of Web bugs has prompted legal inquiries.
Software that gives access to and navigation of the World Wide Web. Using a graphical interface that lets users click buttons, icons, and menu options to access commands, browsers show Web pages as graphical or text-based documents. Browsers let users download pages at different sites either by clicking hyperlinks (graphics or text presented in a different color than the rest of a document, which contains programming code that connects to another page) or by entering a Web page's address, called a URL (universal resource locator). Netscape Navigator and Microsoft Explorer are both popular browsers.
Web analytics refers to a group of statistics Web site maintainers can use to determine what parts of a site are most popular. Such statistics may include the amount of time spent on individual pages, where the visitors originated from, and where they went after viewing the site.
A cleaning blade (sometimes made of felt) that continually wipes a laser printer’s fuser roller. The fuser wand ensures stray toner particles and excess fuser oil do not build up on the fuser.
A war dialer is a software tool used by someone looking to gain illegal entry into a computer system. The program dials from a list of telephone numbers looking for any numbers answered by a modem. When it finds a modem, the number is logged for future reference.
To improve performance. In computing, there are many ways to optimize the performance of your system. For example, you can optimize a hard drive by running a defragmentation program.
A data transfer rating for SONET (Synchronous Optical Network) fiber-optic networks. OC-1 has a transfer rate of 51.84Mbps (megabits per second), about 6.48MBps (megabytes per second), so OC-x describes a fiber that can carry x times 51.84Mbps.
In the strictest sense, to “opt out” means to choose not to participate in something. In the computing world, this term often refers to a user’s decision to not receive emails, marketing materials, or other data from a company that offers that information. These materials are usually associated with some service or product that the end user may want to use or buy. The company will gather some personal data from the user in the course of selling or setting up the product or server and will automatically send the user emails, newsletters, or other marketing data unless the user specifically chooses not to accept that data. Sometimes the user may not be aware that, by providing his personal information, he is giving the company permission to send him materials. Also, the means by which one can “opt out” of receiving such data may not be readily apparent. Some companies will seek a user’s permission before sending the user emails and marketing data. In this case, the user would “opt-in”, or choose, to receive the information.
The order of precedence of operators in an expression. Normally, associativity is left-to-right. Associativity will affect the outcome of the expression. For example, in the expression 9-6+2, where addition and subtraction have equal precedence, with left-to-right associativity, you would first subtract 6 from 9, with a sum of 3, and then add 2, for a final answer of 5. If associativity were right-to-left, you would first add 6 and 2, to get a sum of 8, and then subtract that answer from 9, to get a sum of 1 as a final answer.
The part of a machine language instruction that tells a computer what to do.
An ODS provides short-term storage of operational data. Data stored in an ODS is simple and less complex than data stored in large data wharehouses. As a result, data can be found and retrieved faster from an ODS. Additionally, historical data is not kept in an ODS.
One of two modes, either Standard or 386-Enhanced, that adjusts the way Windows runs, letting it perform its best based on your system's components and software.
The focus of an operation. In mathematics, the operands are numbers or variables, such as 2 or X. In computing instructions, operands are where data is stored, such as Track 1, Sector 7. Also, in programming languages, the part of an instruction that is needed for the instruction to be carried out.
A standard that lets multiple programs work on a single document. The standard is similar to Microsoft's OLE (object linking and embedding) and was developed by several companies, including Apple, IBM, and Lotus.
Source code that is freely available to programmers for use in developing new software. The source is usually in the form of a standard--a sound format such as MP3, for example. It can also refer to an entire program (such as Netscape Communicator) or an operating system, such as Linux. Proponents of open source argue that by letting as many developers as possible work on a program, the software evolves. Developers will fix bugs, add new features, and adapt it for new uses or operating systems. See Open Source Initiative (OSI).
A mathematically intensive graphics language used to create complex, detailed three-dimensional objects, including screen savers.
Additional memory physically located on a CPU (central processing unit). Because of its proximity, the on-chip cache can deliver data to the CPU much more quickly than cache that is off the CPU.
This is an antivirus program that searches a PC's files and programs for hidden viruses. The scanner searches the files when the user opens the file. On-access scanners usually operate in the background, so users normally don't notice them.
Describes the absence of a modem. For example, two computers joined directly by a cable is a null modem setup because neither requires a modem.
To delete the contents of an entire directory or storage volume on purpose. This term is slang, but to be precise, it is never used to describe accidental deletion.
A relatively new breed of trackballs that are portable and the ideal size for notebook computer users. Generally, these trackballs do not consume valuable desktop space; instead, they are handheld.
A simple ASCII (American Standard Code for Information Interchange) text processor included with Microsoft’s Windows family of operating systems. It received an update with Windows 95 but has remained fairly unchanged for years. It reads and saves files with the .TXT file extension. Notepad is often used to get rid of unwanted text formatting by pasting a selection into it and then cutting it out.
A business or group that does not have a Web site.
A software application that converts music entered into a computer using a MIDI (Musical Instrument Digital Interface) device, such as a synthesizer, into traditional musical notation.
When pertaining to information technology, a term describing items contained in industry standards that should be conformed to by professionals or manufacturers.
A term used to describe the method of refining information in a database by placing items into tables with the purpose of ensuring clear, precise results when a user accesses that data.
A term used to describe a virus that activates when the user opens an infected program, wreaks its havoc, and resides in RAM (random-access memory) only long enough to perform the intended operation before turning off. Unlike resident programs and viruses, nonresident infectors do not use TSR (terminate-and-stay-resident) programs to remain active in a computer’s memory and have a much shorter activation time. This fact can make nonresident viruses harder for the user and some antiviral utilities to detect, because the computer’s available memory is only reduced for a short time.
Nonrepudiation simply means that something can not be reputed. In terms of computers, nonrepudiation refers to ensuring that a message is from the party it claims to be from and a way to ensure the message is received by the correct party. This eliminates the ability of the sender or receiver to repute having sent or received an email.
Special command instructions sent with printable data on to the printer. Nonprinting codes regulate the printing format but are not printed themselves.
A way an image is produced and refreshed on a computer screen. In a typical computer monitor, an image is produced by a series of horizontal lines that run from the top of the screen to the bottom. This is known as a raster display. An image is produced or refreshed in a noninterlaced manner when every pixel of every line is updated during every cycle; conversely, an image is produced or refreshed in an interlaced manner when every odd-numbered line is updated during the odd-numbered cycles, and every even-numbered line is updated on the even-numbered cycles. However, this interlaced every-other-line method can cause the screen image to flicker, making it hard on a user's eyes. Therefore, a noninterlaced monitor is preferable.
A method of storing data in which the information is not stored in contiguous, or adjoining, sectors of memory.
A DOS application not designed for operation in a Windows operating system. Non-Windows applications will operate in Windows but will run less efficiently and slower than in DOS.
Any material that transmits electrical currents poorly.
Four bits or half a byte.
A connection point at which information is transmitted between software applications and IBM operating systems (OS/2, DOS, and AIX) on a network.
The condition that can occur when a great deal of Internet traffic or a bad connection slows the retrieval of information from an Internet server.
This term refers to print quality almost good enough for use in business correspondence, therefore suitable for casual use. Near-letter quality was used primarily when dot matrix printers were the most common consumer printer, prior to inkjets.
NHR allows computers to read both cursive and hand-printed text. Unlike ICR, NHR doesn’t place any constraints on where information needs to be written. NHR operates by matching descriptions of an entire word to a list of descriptions in a database known as a lexicon. NHR systems do not look for an exact match because it’s highly unlikely that someone will write a word exactly the same twice. Rather, it matches general descriptions of a word by matching features specific to each word.
A computer application that converts one language (usually a high-end programming language such as BASIC, COBOL, or C++) into binary machine code that a computer can understand. Programs must be compiled (or in the case of assembly language, "assembled"), to function. Compilers are included as a matter of course with programming development kits.
The amount of uncompressed data a tape cartridge or reel can hold.
Describes a transmission channel in communications that has a slow data transfer rate and a smaller bandwidth, particularly any channel with a maximum throughput of 2400bps (bits per second).
A science that showcases the process of building in terms of an object's smallest elements, such as the molecular or atomic makeup of an item.
A unit of time representing one-billionth of a second.
A unit of length representing one-billionth of a meter.
A carbon nanotube with one closed end. The special electrical and mechanical properties of microscopic nanohorns and buckytubes (nanotubes) could usher in advancements in computing and other technologies. In particular, NEC wants to manufacture nanohorns for fuel cells powering mobile devices.
A prefix designating one-billionth of a unit of measurement.
The NAND logic gate is a combination of the AND and NOT logic gates. This gate will first use the AND operator, producing a “true” output when both inputs are “true” and a “false” output in all other situations. The NOT aspect of the gate then reverses this output into the opposite value. For example, an AND logic gate output of “false” will then be changed to “true” by the NOT operator. See logic gate. See AND logic gate. See NOT logic gate.
A type of nonvolatile memory in which the cells are linked serially to each other and the grid of interconnects. NAND is best suited for sequential data reads and writes, as in MP3 players and digital cameras. See NOR flash memory. See nonvolatile memory.
In XML (Extensible Markup Language), a term used to describe a document containing the “rules” and other element data (such as data field names) necessary for sharing information with others on the Web. The namespace’s Web address is usually included in the beginning of an XML document, so that a compatible browser will know how to display the information.
A way for computer processes inside a computer to communicate by sending data through a pipe with a specific name. Any message sent through this pipe can be accessed by any process authorized to do so.
Used in TCP/IP (Transmission Control Protocol/Internet Protocol) connections. Users send requests to the name server asking for help finding a specific computer or piece of information. The name server responds, translating the name of the site on the Web into a computer-comprehendable IP (Internet Protocol) address.
A document that is split into several subdocuments but can still be manipulated in its entirety. Authors of long documents such as novels or theses often use word processing software such as Microsoft Word and WordPerfect to create master documents. For example, an author might set up a technical manual as a master document, with a subdocument for each chapter.
To convert a file into another form. The term can also refer to one of the many different ways files or data are processed, or it may refer to the editing of image or text files.
A filter that holds back certain data and allows other data to pass. For example, when defining numeric fields for a spreadsheet, parameters can be set to disallow certain values that are too high or too low.
Used when adding one or more sheets of paper at a time to a printer rather than using the paper tray. This comes in handy when a different stock or color of paper is required for a single print job.
Software intentionally designed for a malicious purpose, such as to erase a computer’s memory or gain unauthorized access to a system. Trojan horses and purposefully system-damaging viruses are some examples of malware.
In an open source environment, a maintainer is the equivalent to a project leader in the commercial software world. The project maintainer makes all major decisions, resolves important disputes, and ensures that everyone receives the credit they deserve for their contributions.
A mail relay is an email server that delivers messages to their proper destination. A mail relay typically serves a specific local domain that might include an office or a university campus.
A unique set of data that identifies a particular event or transaction between two programs that work together to accomplish a task.
Reading online messages or chat room conversations without taking part in the discussion. Users new to online newsgroups, mailing lists, or chat rooms are encouraged to lurk for a while until they know what the discussion is about. This prevents the same questions from being asked over and over as new users discover the area. In addition to lurking, new users are encouraged to read FAQs.
The brightness of a computer screen, controlled by part of a composite video signal. Also used to describe part of the signal that defines the brightness.
A computer screen or printed page that appears rough, with very little fine detail. Low resolution on a display is the result of too few pixels; low resolution on the printed page is the result of too few dots per inch.
A programming mistake, often caused by the programmer's inability to anticipate every situation that might occur.
Email that is sent to “keep you in the loop.” These messages are often forwarded or CC'ed messages that may or may not have much relevance to your work day and, when sent in large quantities, are often considered counterproductive.
An abbreviation for the phrase "Laughing out loud" that is commonly used in email messages.
A problem in a program that causes it to operate incorrectly, but not to fail. Because a logic error will not cause the program to stop working, it can produce incorrect data that may not be immediately recognizable.
A circuit that performs a processing or controlling function in a computer, in contrast to memory circuits which merely store data.
An error in the logic of a program routine that results in the destruction of data. Unlike a virus, logic bombs do their damage immediately, then stop. Also, logic bombs are unintentional and can be the result of a simple corrupt file.
Starting a computing session or connecting to a computer network. You usually log in to a computer or network by entering a username and password.
A computer file that cannot be altered. Normal users of such files cannot alter the information they contain, change their location, or alter their names.
A change in a program made so it will work better for a specific group or function. For example, localization might include changes that take into account a different language, such as Japanese. One such change might be translating commands in menus from English to Japanese.
More commonly referred to as WLAN. This is a network that uses wireless means to transmit data from one point to another, rather than by using a more traditional wired LAN configuration.
Memory located on the same bus or card as a given processor in a system with more than one processor. Memory that is local to one processor generally is inaccessible to another.
The area on a magnetic tape where information storage begins.
Slang used to describe a person who uses a computer. A computer is the hardware, programs are the software, and the user is the liveware.
Livelock is a condition in which two or more processes constantly attempt to update themselves in response to one another or another process. As a result, neither process completes. This is the opposite of two processes that are deadlocked.
A number or instruction that remains constant and unchanged, even when translated into the machine language used by computers.
In Web design, a “flowing” layout that readjusts to fit any size browser window. Unlike jello and ice fixed-width designs, the liquid layout has no excess margins. However, extremely large or small browser windows can make the site appear sloppy and deteriorate the visual relationship among a page’s elements.
This term refers to links on Web pages that have become outdated as the Web pages the links refer to are moved or taken down. Clicking on such a link usually results in a "This page cannot be found" message.
When ranking a Web site, many search engines, such as Google, factor in the number of sites to which it is linked. Link farming involves exchanging links with other Web sites in an attempt to get a better search engine ranking. Most search engines, however, penalize sites that take part in link farming.
As a noun, refers to a connection between two objects. In data management, a link allows information sharing between a source document and a destination document. Information a user changes at the source also changes at the destination in linked documents. In communications, a link is the line through which data is transmitted. In programming, a link is a connection to another program. On the Web, a link (short for hypertext link or hyperlink) is a connection that takes users to another page. As a verb, refers to the act of connecting two devices or programs.
A graphic created entirely of distinct lines, with no shading.
A single process that slows the larger operation of which it is a part. For example, a slow spell checker can slow down an entire word processing program.
A light-sensitive pointing device that allows users to select objects displayed on-screen by simply pointing to them.
A highlighted item on a computer screen that will appear with a different color to make it stand out from the rest of the screen.
A piece of equipment that transmits light from one point to another. Fiber-optic cables are light guides.
A combination character used with some fonts when two regular characters appear next to each other and bump against each other. For example, a publisher may replace the letters ff with a ligature that connects the short line in the middle of the characters.
Refers to the length of time a key can be expected to be kept in use and still provide adequate security. A key is a special piece of code comprised of a string of bits to encrypt and decrypt data or information for security purposes.
In relation to computers, the words and definitions that make up a programming language.
An alphabetical listing of items. Numbers appear in a lexicographic sort according to their spelling.
This is an email that contains a program or other data that can damage a user's computer. When the letterbomb "goes off," the data may lock up the user's computer or carry out some other undesirable action.
In computer graphics, graphics layering involves working on several layers of a document at a time and then combining the layers to achieve a finished product.
A tool found in many image-editing programs that allows the user to select a specific portion of an image by freehand.
"When logging into a Web site you usually start by submitting your username and password. The server then checks to see if an account matching this information exists and if so, replies back to you with a 'cookie,' which is used by your browser for all subsequent requests."
Most Web sites protect your username and password with a secure HTTPS connection. Unfortunately, many immediately drop back into insecure HTTP once a visitor is signed in — and the site sends its cookie back over a now-insecure connection. Anybody snooping on your conversation can make a copy of the cookie and use it to interact with the Web site in precisely the same way you do.
Unlike Web-crawlers or spiders, which use general criteria to collect data for many users to search through, a knowbot employs an individual’s settings to scour the Internet and present the information for viewing. These programs are also easier to adjust for a specific user and use a more advanced technology than spiders or crawlers. An example of a knowbot would be an application that searches through White Page sites and services for a specific name or a newsbot that collects information from news sites for downloading to a personalized news page.
Industry jargon for a computer application that suddenly becomes so wildly popular that it drives other sectors of the industry. Examples are VisiCalc, the original spreadsheet program, and the Web browser, which changed computing by putting a graphical face on the Internet and making it simpler to use.
Some Web sites determine the relevancy of a Web site to a given search based on the number of times the search terms appear on the page. In order to appear more relevant and gain more visitors, some Web sites stuff keywords into the Web pages. The keywords can be hidden in html (Hypertext Markup Language) so they don’t appear on the Web page. Other sites create text the same color as the background so the text appears invisible to the user. Some search engines may penalize a Web site if it determines it’s using keyword stuffing.
A device used to record a keyboard's keystrokes to track the use of a PC. Parents and some companies use keystroke loggers to keep track of how kids or employees are using their computers. Some Trojan horses are also keystroke loggers, but the purpose of a Trojan horse keystroke logger is generally to collect usernames, passwords, and credit card numbers.
The act of pressing a key on a keyboard to enter data into a computer.
The range of possible variations an encryption key can produce. The keyspace will vary according to the length of the key in bits. A 40-bit key, for example, will have fewer possible keys, and thus a smaller keyspace, than a 128-bit key. The larger the keyspace, the more difficult it is to crack theit encryption.
A small keyboard holding only numbers and arithmetic keys used for data entry. Numeric keypads occupy less space than full-size keyboards, so they are valuable on small desks when only numeric input is needed.
A paper or plastic form placed on top of a keyboard to tell users which keys perform which functions in a program.
A function of most computers that lets users depress and hold a key and, after a short pause, cause the computer to react as though the user was repeatedly pressing the key. Keyboard repeat is handy if a user wants to type an entire line of a certain character, such as a dash.
The dirt, gunk, sticky goop from spilled soda, and other debris that tends to build up on computer keyboards.
A small microprocessor built into a keyboard that passes keystroke data to the main computer.
The length of a key in bits. Also called bit strength.
The act of expanding a key from it original size to create a longer key. A key in this sense refers to a string of bits used to encrypt or decrypt data or information for security purposes. Generally, the longer the key, the harder the key code is to break.
The exchange of keys by two or more parties. In terms of technology, keys are pieces of mathematical code used to encrypt and decrypt data or information for security purposes.
When editing video, jogging changes the position in the video clip by a single frame or a small number of frames.
A unit of work as a computer processes a task.
A computer operation that consists of numerous jobs with different tasks that are processed at the same time.
A plastic case used to protect a CD-ROM or DVD while being transported or stored.
The overload of a user's email program or a network's email server with email messages. Severe cases of overload, caused by such things as spam or viruses, can shut down a server.
An application that provides access to electronic mail (email).
The button pressed to eject a diskette, CD (compact disc), DVD (digital versatile disc), or other removable media from a diskette, CD-ROM, CD-RW, or DVD-ROM drive or other such device.
Software, generally for children, that blurs the line between education and entertainment. These programs combine learning with entertaining activities, such as games.
The edu top-level domain is used to identify educational institutions. For example, colleges and universities use "edu" in their URLs, such as www.hastings.edu. It is not intended for general commercial use.
A switch point at which two networks meet. This is often the point where a smaller network connects to a larger network.
Printing on both sides of a sheet of paper so, when bound, the corresponding pages face each other, as in a book.
Downloading multiple files from the Internet simultaneously and accidentally crashing your computer. You can drownload your system if you download multiple audio files or large image files, and the computer can’t keep up. Your system might stop downloading, freeze, or crash. You can prevent drownloading by downloading only one or two files at a time.
An effect used in graphic design to create the illusion that an image is floating.
The first letter of a text document that has been enlarged so it encompasses vertical space on lines above or below it. Drop caps are used to incorporate graphical elements where there would otherwise be only text.
A program downloaded and installed into a user’s computer without the user’s permission or knowledge. The user receives no warning pop-up or other instruction informing him that a program is being downloaded.
Metal brackets used to mount a hard drive (or other drive) in a computer, in such a way as to allow the drive to be removed easily by sliding it forward. Generally, the rails mount on the sides of the drive and include spring tabs to secure the drive in the computer chassis. This system does away with the need to bolt the drive to the chassis itself.
Any device used in conjunction with a drawing program that allows the cursor to be used as a pen to create and manipulate an image or shape.
The amount of voltage an instrument has consumed from its power source.
In a GUI (graphical user interface), the act of moving an object, or icon, into another object to initiate a process.
An unsuccessful Web-based venture.
An impurity added to silicon during the manufacturing of a computer chip to control how well the silicon conducts electricity.
A textual or graphical compilation of data that is dependent upon an application program for its creation but is treated independently from the application's files for storage purposes.
Application GUIs (graphical user interfaces), or portions of the GUIs, are dockable if they can be dragged and docked (placed at the edge of the screen). For example, you can drag the Taskbar to either side, the top, or the bottom of your screen.
A term used to describe the process of preparing a file for output at one location, then electronically sending it to various locations for actual printing. This allows for a publication to quickly cover a much wider geographic area than would be possible using only one print location.
A system of computer stations in which processing, data storage, and accessibility to databases are shared among individual nodes.
A key that has been divided and then distributed or shared among many users. A key is a special piece of code comprised of a string of bits that is used to encrypt or decrypt data or information to provide security.
A hyphen, automatically inserted by many word document programs, at the end of a line when a word breaks.
A hardware device considered a separate and distinct entity.
The transfer of data to an output component, such as a printer, as a desperate attempt to at least partially recover information that has fallen victim to a disk error or failure.
To turn off a function or prevent an event from occurring. In hardware, disable usually means to unplug or remove a component.
Unlike early jukeboxes, which contain vinyl record albums or audio CDs and play back the audio content based on user specifications, digital jukeboxes store content on a hard drive. Digital jukeboxes are commonly associated with music playback, but digital jukebox content is not limited to audio; it can also include video or any other form of data.
The creation of audio in digital format. In other words, sound represented by the 0s and 1s of the binary system. Special audio software is needed to read audio files.
In a GUI (graphical user interface), an on-screen text box that provides users with information and explains possible options. For example, a dialog box for a wizard in a word processing program might provide choices between creating a fax cover sheet or a business letter. After the user clicks an option, the dialog box would present another set of options, such as a list of formatting styles. Dialog boxes filled with options would continue to appear until the document is created.
A device driver is a program that allows a hardware peripheral, known as a device, to communicate with a computer. Device drivers typically come with the device, and updated drivers can be obtained through the manufacturer's Web site.
A general name for a group of devices. For example, all keyboards are input devices.
An external hardware apparatus that attaches to a computer to allow it to send or receive a specific type of data. A printer and a modem are two examples.
The site to which data are directed. A site can be any hard drive, disc, file, directory, or document within the computer or online.
A filter found in some photo editing programs that removes small, unsightly speckles, or bits of grain, from an image to improve its quality.
Refers to a Windows Desktop, the first screen you see when the OS (operating system) is opened. The Desktop always includes several items including the Recycle Bin, the Start button, and the Taskbar.
A method of arranging data in reverse alphabetic, numeric, or date order. Examples include a numerical sort from 10 to one and an alphabetical sort from Z to A.
A character that relies upon a previous operation to determine its value.
A symbol, such as a comma, that programmers use to separate data in code.
The keyboard key used to erase individual characters to the right of the cursor or highlighted strings of characters. This key can also delete files selected by a user.
Using tools found in an image-editing program to alter, or deform, the data that makes up a digital image.
A method of preventing future defects by maintaining a database of prior defects.
The standard setting, predetermined by your computer, that is engaged when the user fails to denote a specific alternative. Defaults generally are the most often used settings for a particular program.
Hackers who break into a Web site often vandalize or deface the site by replacing the site's content with their own. The content can sometimes be humorous or political in nature.
The nature of the web allows the creators of one Web site to link to content within another Web site regardless of where the information might be. A deep link is any link to information on another page or Web site that is not the site’s homepage.
A device that serves only one purpose.
The process of translating encrypted data back into their original language.
When you deboss a logo or other design, you create a depression into the surface of the paper. This is the opposite of embossing, which creates raised edges.
An error that occurs when two programs are each waiting for a signal from the other to proceed. Also called deadly embrace.
A key that has no function when pressed by itself but produces an effect when pressed in conjunction with another key or keys. One example is the SHIFT key.
Any mechanism that directs data to various locations. For example, a data switch allows a single computer to send data to multiple peripherals, or it allows multiple computers to share a single peripheral.
The part of a cache that holds actual lines (cache lines) of data.
The electronic form of paper shredding. Letting a computer user destroy a file to render it unusable.
The mutual use of a single file on more than one computer or by more than one person or organization.
The part of storage or memory that retains data required by a program.
In a database management system, the act of recalling data from a database.
Within a computer system, the precautions taken to maintain data integrity and minimize errors.
Multiple pieces of data that have been joined together and treated as a single item when passed between network sites.
A diagram used to illustrate how data travels through a system, such as where data is stored or processed, and the path that the data follows as it travels through the system.
The movement of information through a computer system.
In a database management system, an area within a data record reserved for a small specific piece of data such as a date.
The path data follows when traveling between two peripherals.
The accumulation of information in a form that can be used by the computer. For instance, data capture occurs when an analog-to-digital converter translates normal audio into digital signals the computer can process and manipulate.
A small, high-memory storage area designed to speed up access to stored video files. The video cache, which is much smaller than a hard drive, takes considerably less time to load and retrieve files.
A programming term that refers to a pointer whose target has either been moved or erased.
The amount of time between one RAM access and the next.
Combining the words "cyber" and "librarian," a cybrarian is a professional who is adept at using the Internet for research purposes.
To modify or set up hardware and software according to an individual's preferences.
A marker on-screen that shows where current input or output is going to happen. It may appear as a blinking vertical line, a solid or blinking box, an underline, or a caret.
A downloadable file found on the Internet that is falsely named. These files are created by people as a practical joke and are commonly found at Web sites that offer free music downloads. For example, you might think you are downloading an MP3 of “American Pie” by Madonna, when the file is actually “Easter Parade” by Perry Como. Also an MP3 file that has been altered to render it useless. For example, the first few seconds of a song may be followed by four minutes of white noise. The idea was conceived by those running the Cuckoo’s Egg Project to slow the spread of copyrighted material through services such as Napster. No harm is intended; this tactic simply wastes the time of the person who downloaded the file in an effort to discourage them from trying again. Oddly enough, cuckoo eggs themselves are illegal because they contain a snippet of a copyrighted song.
A key on a computer keyboard that, when used in conjunction with other keys, gives a key a function other than its labeled one. For example, in Microsoft Word, pressing the CTRL key with ALT and the minus sign (-) on the numeric keypad produces a long dash (--). The CTRL key generally is on each of the lower corners of the main section on a keyboard.
The study of encryption and code breaking.
To process information. A number cruncher is a device or routine designed for rapid processing of numbers.
Slang for two bits, or two binary digits.
A set of crossed lines that takes the place of the cursor in some programs. An operation will take place at the point of the intersection.
To trim an image to refine it for use in a document. Backgrounds, individuals, or objects may be cropped out of pictures. Cropping may result in a less-cluttered or more powerful image, but it also can create a misleading picture.
Often associated with freeware or shareware. Some companies offer free or trial versions of their software to entice users to buy a full version. The trial versions do not have all of the features and functionality of the full versions, thus they are crippled versions of the program.
Spyware and other malware designed for criminal purposes such as fraud, identity theft, and theft of funds. The term crimeware may also cover other types of software if used for illegal purposes, such as antiforensics.
A CPU (central processing unit) shim is a thin piece of non-conductive material, copper, or other material that is completely flat and is installed between a CPU and a heat sink. If used correctly, CPU shims prevent damaging the CPU when installing the heat sink. CPU shims are sometimes called CPU spacers.
Educational or training software used in schools or other training facilities to teach about a specific topic.
A program routine that is repeated a specified number of times. A counter variable is increased by one each time the routine is performed. When the variable reaches a certain number, the routine ends.
The damage or alteration of data or programs because of hardware malfunction, software failure, viruses, power failure, human error, or deliberate sabotage.
To alter or partially erase information in memory or a file, rendering it unusable by the computer. Hardware or software failure can corrupt a file by rearranging the bits of data. Corrupted information no longer is readable.
Diagnosing and fixing computer problems instead of preventing them.
A visually busy Web page or ad that incorporates so many colors, graphics, fonts, and other visual devices that it becomes confusing or unattractive.
Describes two or more programs that reside in memory at the same time. This term can be used to describe two or more things in the same place (such as a computer or a network).
Hardware or software that protects programs from being copied without authorization. Copying commercial software for reasons other than personal use is a violation of software licensing agreements and is illegal.
An operation mode in which multiple computers work on different parts of the same program or on the same data.
Hardware or software that changes information or electrical signals from one format into another for use by a system or device requiring a format other than the original.
An interactive mode of operation in which a computer is interacting with the user in an exchange of commands and system responses. PCs operate in this mode.
A standard, whether formal or informal, that is applied fairly universally in a given situation. For example, programming languages rely upon conventions that define the meanings of certain symbols and abbreviations.
A measure of how much darker a monitor’s darkest black is compared to the monitor’s lightest white. For example, a monitor with a contrast ratio of 250:1 has black dots 250 times darker than its whitest dots.
Representing the quality of an object's surface in computer graphics. Shows whether an object is rough or smooth.
Processing transactions as they are entered into a system, as opposed to batch processing, in which transactions are processed in groups (or batches).
A set of information stored in consecutive memory locations.
Side by side. Two or more items are contiguous if they are touching each other. For example, contiguous sectors on a disk are physically next to each other.
In data processing, a group of data fields that may be processed one after another, in sequence.
A help menu that refers to the choice or area of a program currently selected. This type of help is useful because the help refers to the item in its current context.
A kind of multitasking in which the computer moves from one task to another as necessary, instead of giving time to each task in its turn.
The menu that appears next to the on-screen pointer after a user right-clicks. For example, if a user right-clicks the Windows 7 Desktop, a context menu will appear with options such as Screen Resolution, Gadgets, and Personalize.
Materials used in the process of performing a task. For example, ink, paper, and toner are considered consumable items for printing tasks.
The amount of time a user spends connected to a remote computer, particularly referring to how long someone is on the Internet with an online service or Internet service provider. Connect charges often are based on connect time although some have a flat monthly fee for unlimited connect time.
An overload of data on a communications path. Congestion caused by a high volume of traffic on the Internet, for example, sometimes results in network slowdowns.
A type of software that translates and passes data between a desktop computer and a handheld device.
The status of an expression or variable. Examples are true, false, equal, and not equal. In some programs, instructions take place based upon whether a certain condition is true.
A font style that reduces the width of each character and places the characters closer together, allowing more characters to fit on each line.
An operation in which two or more programs have access to the microprocessor and are carried nearly simultaneously. Although the operations are not truly taking place at the same time, the difference between how a computer manages time and how people perceive it makes it appear simultaneous.
The use of a computer system, program, database, or other resource by more than one user at a time.
A device that combines communications signals from several sources, such as computers on a network, into fewer signals before transmitting them to the destination. Also can refer to a hardware device that connects several peripherals to a computer with only one line between the concentrator and the computer.
The ability of computers to accept visual input; or, components that let computers accept visual input. CV hardware and software developers form a large group with diverse interests. For example, some CV developers are interested in industrial applications (such as monitoring factory lines for product control), while other CV developers pursue highly technical endeavors (such as using CV to aid nanotechnology to give "sight" to tiny robots, or for artificial intelligence applications).
html (Hypertext Markup Language) tags that have open and close code.
A document that contains data from two or more applications. For example, a word processing document that contains a chart from a spreadsheet program is a compound document.
In image editing, this is the process of combining several images or specific portions of images into one overall image.
A measure of how well two or more devices (hardware or software) work together. For example, two programs are compatible if a file created in one can be read in the other. Compatibility also can refer to how compliant a device or program is with a standard.
The line on which the user types commands to be carried out by a program. This is a feature of a text-based interface such as MS-DOS, as opposed to a GUI (graphical user interface) such as Windows.
An image on transparent film that produces a normal, positive picture when light is shone through it. A photographic slide, for instance, is a color transparency. Photographic negatives are the opposite of transparencies.
Literally, the degree of "color" in a color. Higher saturation means a higher degree of color.
Refers the multiple passes a scanner must make before a duplicate image achieves the same color quality as the original.
A technique that lets remote users take control of your computer as if they were using your keyboard and mouse. It’s sometimes used by companies to help customers troubleshoot problems they are having on a Web site or on their computer.
A section of code that contains specific operations or instructions for a software program.
Refers to the garbled-looking characters in a computer security code system. What looks meaningless actually contains plaintext elements that refer to words, phrases, or numbers.
A collection of programming code. Code libraries simplify programming by providing access to frequently used routines and functions.
Code forking refers to branching a program in multiple directions. This often happens when a considerable number of people want to add new features to a program but the developer does not. Code forking most often occurs in programs that are in the public domain or are open source.
A cluster is made up of a group of sectors found on a diskette or hard drive. Each cluster is assigned a number by the operating system. When you access a file, the operating system retrieves the file by accessing the clusters the file uses.
The smallest unit of time recognized by the CPU. Also called CPU cycle.
The act of hiding your name and email address in an email. Individuals who distribute bulk unsolicited email often cloak their real identities and email addresses to avoid retribution from those angry over being "spammed."
Mass-produced artwork available for authorized users to incorporate into their own publications.
In the days before publications were assembled by computers, publishers and graphic art companies often subscribed to clip-art services that sent an assortment of artwork each month, printed in booklets or on loose pages. Rather than creating all artwork from scratch, publishers had the more budget-conscious option of clipping an illustration off a sheet and pasting it into one of their own pages for reproduction. Hence the name, clip art.
Although printed clip art is still available, most of it now comes in electronic form. Desktop publishing software usually comes with clip-art collections, and a variety of clip art is available for the professional and casual user alike. Clip-art services still provide electronic or printed artwork by subscription, and there are clip-art packages available for individual sale, as well. In addition, there is a a great deal of artwork available online for downloading, either for free or at a modest cost.
Clip art is subject to the same copyright law as any other published material. Those who buy clip-art packages, or software that includes a package, are purchasing the rights to use that artwork. Rights, however, are not always unlimited. Many packages have stipulations on the way the art may be used.
A term that refers to a user who is clicking a mouse button very quickly.
A compilation of all of the links a visitor clicks during a visit to a Web site. The information is used by marketers to determine visitor preferences.
A closed-in area containing sensitive equipment. The air is filtered to keep out dust and other particles, and people wear protective clothing to avoid inadvertently contaminating the equipment. The computer facilities of many companies, particularly those with important data such as customer accounts, are set up as clean rooms, as are areas where highly sensitive equipment such as microprocessors are made.
A blog that is not open to the public. Often blocked by a firewall.
A series of references in which the last reference points back to a previous reference in the same series. Alternately, a circular reference can mean a data entry mistake, usually in a spreadsheet, in which a formula is told to act upon itself or an element of itself. For example, setting a formula that multiplies two cells and then asking that the result be placed in one of those two cells is a circular reference and probably was a typing error.
In printing, cibachrome is a color printing process that produces high resolution prints directly from color slides, transparency film, or digital film.
The purity, or quality, of color. Chromaticity is defined by wavelength and saturation.
A line that connects the two endpoints of an arc. When referring to mice, a chord is a simultaneous click of the left and right mouse buttons.
A program that uses artificial intelligence software to interact and hold conversations with human users. Examples are the Eliza and Alice programs.
A calculated value transmitted with data to check for errors in the transmission. There are several ways to calculate a checksum. In a simple example, the number of bits of information is added, and that number is sent with the transmission. The number of bits in the message is recalculated at the receiving end, and if it matches the original checksum, the information is considered error-free. (The procedure is the same regardless of which mathematical operation is used to find a checksum.)
A transaction file in which changes to a database are logged. The change file is then used to update a master file. Also called a transaction log.
Linking two or more things together so that they depend upon each other; one program causes another to execute. Within a program, statements are considered chained if all but the first statement depends upon the previous statement. Segments of data storage are considered chained if, for example, a single file occupies several sectors, each of which points to the next section of the file and its location in memory.
The byte in a date field that indicates the century. For example, the 20 in 2002.
A derogatory term used to describe Internet filtering software by those who oppose such software. Internet filtering software blocks access to sites deemed inappropriate and is used to keep children away from adult or other inappropriate material on the Internet. Censorware opponents claim that such software does a poor job of filtering content correctly, allowing viewing of some inappropriate sites and banning some legitimate sites.
A silicon junction in a memory module’s grid of rows and columns. Volatile memory, such as RAM, and non-volatile memory, such as flash, both store bits in cells as electrical charges.
Prior to LCD (liquid-crystal display), the display screen commonly used in televisions and standard computer monitors. An electron beam moves across the back of the screen, lighting up phosphor dots inside the glass tube, which causes an image to be displayed.
In images, the cast is the emphasis of one hue or tint that overpowers any other hue or tint.
The housing for the computer. Also refers to the format of a letter, as in whether a letter is uppercase (capitalized) or lowercase (not capitalized). Uppercase letters are A, B, C, and so on; lowercase letters are a, b, c, and so on. The term comes from the early days of printing, when individual letters were stored in trays or cases, with the capital letters in the "upper case," and the non-capitalized letters in the "lower case."
The symbol usually found on the number 6 key at the top of the main part of a computer keyboard. Some programming languages use the caret as an exponential operator. For example, the phrase 4^2 means the number four to the second power, or four squared. In computer instructions, the caret often is used to represent the CTRL key on the keyboard.
To move received data into a file for storage or later use. Sometimes this refers specifically to saving all the information that appears on your screen during a communications session so there is a record of the online "conversation." The term also can refer to a screen capture (also called a screen dump), in which the image on the monitor is captured as a graphics file.
A button in almost any dialog box in a GUI (graphical user interface) that lets a user exit the dialog box without making any specified changes. It returns any settings to their status before the box was opened.
Fonts that simulate the flowery calligraphy. Sometimes called script fonts.
To open a program, file, or document. This makes it appear on-screen and ready for using or editing.
If your young son receives an invitation to a party that’s BYOC, don’t be worried. BYOC stands for bring your own computer. BYOC is a common phrase used by gamers when hosting a LAN (local-area network) party. At LAN parties, a group of people get together to play computer games and compete against one another using a common local network. Because each player needs his own computer, guests are asked to bring their own.
A condition in which a bright unchanging light on some types of computer displays can, over time, permanently burn an image into the phosphor coating inside the display tube. Burn in can be prevented by turning off an unused monitor or using a screen saver, which continually changes the image to prevent one picture from appearing on-screen for too long. Burn in is not much of a problem with newer computer monitors.
A small graphical element used to set off items in a list. Classic bullets are small filled-in circles, but bullets also can be squares or other shapes. Bullets often are used in word processing and desktop publishing applications.
A device that uses electromagnetic energy to erase data from a magnetic storage medium such as diskettes or hard disks.
A flaw in an application or piece of hardware that causes a persistent malfunction or undesired result. Software bugs can be corrected by rewriting the software code. Hardware bugs are corrected by redesigning the hardware. The first computer bug is said to be a moth found in ENIAC, one of the first digital computers, in 1945. The moth caused a malfunction after being crushed between two electrical contacts. The term itself is older, however, and some sources trace it back to the 1800s.
When a buffer receives all the data it can hold, it will stop accepting data. If it continues to accept data, the overflow will cause a loss of data and can crash the system.
A colloquial term for storage. A hard drive or other mass storage medium can be referred to as a bucket for your information.
A self-replicating worm that emerged in 1999 with the power to spread via email to Microsoft Outlook and Outlook Express. Unlike previous email borne viruses and worms, BubbleBoy could infect a computer even if the user didn’t open any attachments. Merely opening an infected email in Outlook or even viewing the message in Outlook Express’s preview pane was enough to activate the worm. Once activated, BubbleBoy would attach itself to the user's address book and send itself to everyone on the list. Although BubbleBoy itself wasn’t harmful, and although it wasn’t initially found “in the wild” (that is, at large on the Internet), it was considered to be an ill omen of malicious viruses to come.
The small bubble or text box that appears when a user hovers a mouse cursor over an item in a graphical interface. This information is typically timed to disappear after a few seconds.
The process a Web site employs to detect which version of a browser a visitor is using. This tells the site if a visitor’s computer can handle more complicated multimedia presentations or just a simpler version of the site.
To view data, usually in such a way that you can page through screens or windows quickly. Today the verb is associated with looking at sites on the World Wide Web.
A temporary, partial loss of power, ordinarily because of a dip in the power supply level. This is different from a blackout, which is a temporary but complete loss of power.
An especially bad or embarrassing bug found in a computer program. The bug is so egregious that it may make the programmer want to put a paper bag over his head.
Traditional "brick and mortar" companies that have ventured into the world of e-commerce. Bricks and clicks have both a physical presence, such as a department store in a mall, and an online presence through which they sells goods or services.
Used on a Web site to let you know where you are and how to get back where you were. For instance, the Open Directory Project (dmoz.org) lists the section and subsections of the directory you’re exploring as you navigate the site. A bread crumb trial might look something like: Computers: Software: Operating Systems: Linux: Distributions: Debian.
To test every possible action a program might perform.
A graphical area that appears on-screen, usually with information or a request for user input, in a GUI (graphical user interface). Boxes are different from windows in that they usually cannot be resized or otherwise manipulated. Boxes are part of an application, whereas windows usually contain an entire application. In some instances, a box might also be a synonym for "computer," for example, a Macintosh box.
A method of writing that moves from left to right on the first line, but from right to left on the second line, and so on. Some printers, especially older ones, would follow this pattern when printing text.
Computer software has traditionally handled on-screen objects (such as clip art images) by putting a bounding box around such objects. When you click a graphic in a program such as Word, you’ll see the bounding box.
In program design, a process in which the simpler programming is designed first and the more complex programming is designed afterward.
An illegally reproduced copy of a piece of software. Many manufacturers attempt to foil bootleggers by incorporating anti-copy measures into their products, but nearly every useful program is copied by someone eventually. Software developers consider bootleg copies produced in large quantities by rogue manufacturers in the United States and other countries a significant problem.
The boot sequence defines where the system looks for the OS (operating system). The computer’s BIOS (Basic Input/Output System) can be set to look for the OS on drives in a specific order. For instance, the BIOS may be set to look for an OS on a floppy drive, then check the CD-ROM drive, and finally check the hard drive for an OS. The boot sequence is generally configurable.
The primary hard drive on a user’s computer; the drive that contains all the startup information. If the boot drive isn’t working, you won’t be able to start your PC normally. Most PCs designate the C: drive as the boot drive.
The part of a disk that contains the software that enables a system to start. The boot block typically includes an operating system.
(Pronounced BOO-lee-un.) An adjective describing an expression that results in a value of either TRUE or FALSE. Named for mathematician George Boole, the word describes a common system of logic using mathematical expressions. It uses a defined set of operators such as AND, OR, NOR, and NOT. Any expression that contains relational operators such as the more than (>) sign are considered Boolean, because of the result being either TRUE or FALSE. Boolean expressions are used extensively in search engines on the World Wide Web. For example, if users are searching the Web for information on singer Tina Turner, they might type "Tina AND Turner" into the search box. This is a Boolean expression that will retrieve only documents containing both the words Tina and Turner. If the user does not want to read about Turner's Australian tour, the Boolean expression to be entered might be "Tina AND Turner NOT Australia." Documents that meet these criteria would be "true" and all others would be "false."
User-definable lists that allow a person to display easily a certain location within a document or a page on the World Wide Web. Clicking a bookmark usually calls up the location it references. Bookmarks often are used in connection with Web browsing programs such as Internet Explorer. The lists let users point and click on names of locations instead of typing addresses or paging through screens of text.
An unusable or obsolete piece of hardware.
A case mod (modification) whereby a cooling fan is installed in the side panel or top of a desktop system's case. Sometimes the blowhole is positioned near the CPU to help keep the CPU cool. A blowhole positioned in the top of a case is called a chimney fan.
To check data, either through software or manually, to see if it adheres to certain standards. A diskette could be checked for corrupted information, or information could be checked to make sure it adheres to the standards for a program, such as numbers falling within a designated range.
A data feed produced by a blog. It is designated by a URL, and is usually in an XML-variant format like RSS. Blog hosting software produces a machine-readable version of the blog that can be further used on the Web.
A group of data with a beginning and an end, usually occurring within a larger amount of data. Many users with word processors manipulate text blocks consisting of words, sentences, or paragraphs by highlighting them with the cursor and then cutting, copying, and pasting them. Spreadsheet users might highlight blocks of cells, columns, or rows to perform similar operations. Data also are saved in memory in blocks.
A slang reference to software that requires a lot of hard drive space and random-access memory (RAM) for features that may be seen to have dubious value. Bloatware is a consequence of Parkinson's law, which says resource requirements grow as the available resources grow. In other words, as soon as you add a faster processor, more RAM, and a bigger hard drive, software makers will find a way to use it all. The major Internet browsers and office suites often are tagged with this epithet. There is a reaction to this phenomenon primarily by smaller software makers, who deliberately produce applications with tightly focused functionality and moderate to low hardware requirements.
An abbreviation of blind carbon copy, a feature found in many e-mail client programs. Recipients addressed under Bcc: will get the message, but other recipients under To:, Cc:, and Bcc: will not be aware of this. Bcc is a tool for sending someone a copy of an e-mail message without anyone else knowing about it.
Can be used in a variety of contexts, but it may refer to a list of abusive users who are banned from a Web site, newsgroup, etc. It may also refer to a list of blocked email addresses.
A hacker who intrudes into a system with intent to cause harm. Black hat hackers may simply steal data or they may deliberately destroy files.
The number of bits transferred in a certain amount of time. The most common unit of measurement for data transfer is bits per second.
In the field of computer security, biometrics is an authentication technology in which computer identification of physical characteristics replaces passwords. For example, biometric scanning devices can identify users by their retinas or fingerprints. Biometric devices and techniques are expected to be applied increasingly in the area of e-commerce to boost the security of online transactions.
The name of a number system made up of only two digits, usually 0 and 1. Any number can be represented in the binary system, although larger numbers are much longer than when expressed in the more familiar decimal system, which uses 10 digits (0 to 9). Computers use the binary system extensively to store, receive, and transmit data. The number "1" in binary is written as 1. The number "2" is written as 10, where the one is in the "twos" position and a zero is in the "ones" position. The numbers one to 10 in binary would be: 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010. If a set of letters is numbered, letters also can be stored in binary format.
An image that only has black and white pixels.
Slang for a software design that attempts to integrate features from two distinct products into a single release.
An effect used in graphic design to make an image appear three-dimensional.
Slang terminology used to describe a situation in which a technology or standard, usually of superior quality, becomes obsolescent because a competing technology or standard becomes more widely adopted.
Errors or flaws discovered in a software program during its prerelease period, often called the beta.
A slang term that refers to freeware, which is software that developers give away. With beggarware, however, the programmer practically begs for donations in exchange for the program.
An audio result of the POST (power-on self test) that a PC completes as it starts up. The number of beeps indicates a particular problem. Typically, a single beep means the computer is functional.
A term used to describe the area toward the front of a computer typically where the disk drives and CD-ROM drives are housed. Bays usually are stacked on top of each other. The word comes from the telephone industry, where equipment was mounted on racks in similar bays.
A computer task that requires no input or other type of interaction with the user. Often, batch programs involve sorting or printing items in large databases. Batch programs sometimes run as background processes at predefined times.
An imaginary line with which typed letters are aligned. The bottom of a letter usually touches the baseline. Descenders, such as the bottom of a "j," drop below the baseline.
A term used to describe a monitor screen distortion where both sides of the display appear to bulge at the sides and/or along the top and bottom.
A standardized system of representing data in the form of parallel lines of different widths and spacings. With the correct equipment, a computer can read bar codes, which often are used to identify objects for inventory and to track shipments. One everyday use of bar codes is at the grocery store, where nearly every package includes a bar code that computerized cash registers use to find price information and to update inventories.
Slang for a Web site that stores pirated files. The site promises access to the files if you click through a number of banner ads, a process that’s usually unsuccessful.
A script included in Web pages that automatically changes the banner ad that a user sees at a particular Web site. The banner ad rotator will show a new ad to the user whenever he visits the site or refreshes the Web page.
A flaw in a printed document characterized by noticeable vertical or horizontal lines running the length of the page.
The process of sending data through a network on a less-than-direct route. The idea is to avoid network congestion and perhaps save time and money.
In reference to text, alignment is the arrangement of characters according to a particular point of reference, such as the left or right margin.
An alternate name assigned to a computer, file, object, or group on a network. Aliases are handy when they replace a long name or a list of names. Many email programs let users assign an alias to lengthy and cryptic email addresses. For example, a user could send an email message to "Joe and Sally" rather than firstname.lastname@example.org, and the message would be sent to the complete address. Macintosh and Windows systems let you assign aliases to files, so you can have icons for the same file in different folders. Unix also supports aliases.
In a GUI (graphical user interface), a box that displays a message to warn the user about a potential or real system error.
An additional layer of security in a computer network, in which some LANs (local-area networks) that are part of a larger network are not connected to each other or to the Internet. This helps keep some parts of the network secure if other parts are compromised, but to some degree, it limits the communcation among the LANs.
A collection of data objects in a programming language.
A slang term used to describe free, sponsored software that often, but not always, contains cookies and Registry keys that are loaded onto your computer when you install the main program. This data is then used to track your Web movements and/or target ads to suit your tastes and needs. Sometimes, uninstalling the original software will not remove the cookies and Registry keys from your system and will still let advertisers track you. However, you can use programs, such as Lavasoft’s Ad-aware, to remove these sticky components for you.
A cursor that may be directed immediately to any location on the computer screen. Normally this is accomplished using a multiple key combination. For example, using the CTRL-HOME key combination will position the cursor at the top of most word processing documents.
The maximum number of pixels a monitor can display. The more pixels there are on a screen, the closer together they are, and the more precise the picture looks. Also known as resolution.
A portion of a computer's memory reserved for keeping track of the location of data in memory.
The practice of changing your email address when you post it somewhere on the Internet, such as on a forum, Web log, or online form. A human wishing to reply to you will understand that the extra characters you type after the @ sign in your email address, such as the “NOSPAM” in yourname@hotNOSPAMmail.com, are extraneous and will leave them out of your address in a message to you. However, an automatic email address retrieval bot or spider may not be able to make the distinction, especially if you use a more unusual munging phrase than “NOSPAM.” Some Web administrators caution that munging may protect your inbox, but it does nothing to deter the spammer and actually just creates more undeliverable messages administrators must deal with.
An automated program that scans newsgroups and Web sites for email addresses. In many cases these addresses are used to send unsolicited junk email.
A feature of most email programs that lets users maintain and store multiple email addresses. The address book enables users to easily send an email message to multiple recipients. It lets users click the addresses they want and then their email program automatically adds each selected address to the header or the To: field.
In data transmission, adaptive compression selects a compression algorithm that best suits the characteristics of the data, choosing the one that offers the fastest transmission speed and optimal compression.
A bridge in a network that is programmed to “remember” destination addresses, which significantly speeds up subsequent transmissions.
A small piece of computer code, usually written in html (Hypertext Markup Language), that advertisers give to the Web publisher that hosts their advertisement. When a user comes to a Web page and clicks the ad, the ad tag directs the user’s browser to the advertiser’s server to retrieve the body of the advertisement.
The ratio of active records to the total number of records in a file, useful in determining the load on a database.
Any data file that currently is open and able to receive or transmit data.
A connection or line of data that is currently in use. This term often refers to channels that are streaming data over a network.
Describes an application or file that currently is operational.
Any distinct and executable command that initiates an action for the computer. The command might consist of a single word or a series of words and might perform one action or a number of related actions. An example is the clear command, which in many computer languages clears the screen. An action statement differs from an expression, which designates a value instead of performing an action.
Acronyms are abbreviations of terms or phrases that are pronounced as words rather than individual letters. Two common acronyms are WYSIWYG (What You See Is What You Get) and RAM (random-access memory).
The length of time that is required for a computer system to process a data request and then retrieve the data from memory, a storage device, or the Internet. This access time can range from a few nanoseconds when accessing a file in the computer's memory, to hours when retrieving a large amount of data from the Internet.
The rights a user or computer has to open up a communications pathway with a particular computer, component, or application. Limiting access rights keeps specific people, machines, or groups from using a certain network, machine, or files. Access rights usually are controlled through the use of passwords and codes.
In an 802.11 wireless LAN (local-area network), the hub through which different devices using the network communicate.
Different permissions associated with files to determine how they can be used. Such permissions include write, execute, and read. Some users may not have all the permissions associated with a specific file available to them.
A device or software driver that allows one component or application to communicate with another. For example, an access arm positions a read/write head for communication with a hard disk; a device driver allows a software application to communicate with the computer system.
The ACL is a list noting which users have access rights to network resources. Specific users, for instance, may have access to company payroll information while other users are restricted from accessing such information. Different users may have different rights to a specific resource. Some users, for instance, may only be able to read a file while other users may be able to read and write to a file.
The ability to allocate computing resources based on a user's identity. A simple example is the setting of a password on your computer that keeps it from working until the password is entered. Administrators also can use special software on a network to customize access according to user identity. Such software usually allows levels of access to be set.
Also known as TOS (terms of service). Many ISPs (Internet service providers) have an acceptable use policy that their customers agree to abide by. The AUP defines specific activities that a user cannot use his Internet connection for, such as hacking Web sites or using the ISP for illegal purposes.
Software developers use abstraction to identify similar features and processes in software code in the hopes that the instructions can be combined. The idea is to make the software more efficient and effective.
A comment you would type into the subject line of an e-mail message to tell the recipient that you won't be online for a while, due to network problems or because you're moving or sick or some other reason, generally beyond your control.
A term borrowed from print media that indicates the portion of the screen the user sees first. On Web sites, important information should go in this space, but it’s also expensive advertising real estate. In order to be above the fold, the information should be visible without having to scroll vertically or horizontally. Since users can have various screen resolutions that affect whether something is positioned above the fold or not, it is important to know the resolution used by most visitors to the site.
A DOS error message that appears when a nonfunctioning drive has been accessed. Some form of this message most often appears when a user attempts to access an empty diskette drive.
Extremely common words that a search tool sometimes omits, including “and” and “the,” among others. Placing the words in quotation marks sometimes forces the engine to find them.
Sharing of licensed content among Web sites. Supplying material for reuse and integrating it to fit the desired content.
Symbolic links are also known as shortcuts. Symbolic links shortcut to other files. For example, the icon on your shortcut that opens your My Documents folder is a symbolic link.
Allows users to send short (160 character) messages from an enabled electronic device to a mobile user. When a message is sent to a mobile user, it first travels to the Short Message Service Center (SMSC), which then contacts the home location register to find the status of the mobile user. If he or she is not using the device, the home location register will let the SMSC know the user is not active and the SMSC will hold onto the message until the user accesses his or her device. At that time, the home location register lets the SMSC know the user is active and the message is delivered.
In both negative and print format, this is the luminance difference between the lightest and darkest areas.
The highest amount of electrical current a conductor can support. Also, a measure in desktop publishing of how much hue is in a color. For example, if a mixed color is 90% red, it has a red saturation of 90%.
An intelligent hub serves as a central connecting point for a network. It is “intelligent” in that it’s capable of more complex functioning, including switching, routing, bridging, and even LAN emulation, among other possibilities.
A general term for money in a monetary transaction that takes place using the Internet. Also called cybercash and e-money.
A name, label, or title given to a function or variable.
Storage not currently accessible to the computer, such as files on a diskette that is not in the diskette drive.
Software for which businesses buy licenses but don't use.
A device that expands the number of peripheral units a user can connect to a single port, usually on a portable computer. An expander makes it possible to connect additional devices, but only one of those devices can operate at a time.
As an operating system writes to and deletes data from the paged pool in RAM, gaps appear between blocks of data that are still current. New data larger than the existing gaps is often written piecemeal, as space allows, leading to the condition of pool fragmentation.
Files are transferred through the Web using packets, which are reassembled, piece by piece, at the destination computer. If a packet is delayed, the final document can’t be reconstructed, causing a packet jam. Clicking Reload or Refresh requests that the file be sent again, which should fix the jamming problem.
An access point onto a LAN (local-area network).
An electrical impulse used to send data to and from various devices in a PC, or across cable or wires. One example is the analog signal sent by modems over phone lines to establish a connection with an ISP (Internet service provider).
A set amount of stored information in memory. In word processing and graphics programs, a page is the amount of information on-screen that would take up one printed page. On the Internet, a page refers to a single World Wide Web page.
As a verb, to move the beginning of a line of text inward from the margin. As a noun, the space created by such a move between the margin and the beginning of text. A typical indent is five spaces. In many programs, users can press the TAB key to create an indent.
Describes two electronic devices that have the same type of connector pins, with the same input and output abilities. These two devices can replace each other and can be plugged into the same socket.
A block of data transmitted from one computer to another on a network or on the Internet. A packet contains three parts: the data to be transmitted, the data needed to guide the packet to its destination, and the data that corrects errors that occur along the way. Several packets make up a typical transmission. The computer splits up the transmission at the transmission point and reassembles it at the destination.
A switch or dial connected to a PC fan. This switch lets you control fan speed, and thus, noise levels and temperature inside the PC case.
An air circulating device inside a computer case that cools heat-generating components. Usually, these fans are built into the power supply of a computer. Modern CPUs run at very high temperatures and often require two or three fans to cool the components.
A storage area for paper in a copier, printer, or multifunction device. It can usually hold 100 or more sheets of paper and includes a sensor to determine when the paper runs out.
Papers are classified into different grades by the materials used to make them. Papers are also graded differently depending on the intended purpose.
A state of low-power inactivity. PCs and peripherals with sleep capability can be set to enter an energy-saving mode in which all but vital functions are shut down until the user "awakens" the machine. For instance, a monitor might go blank when in sleep mode. Often pressing any key on the keyboard will end a computer's sleep.
An ad view occurs whenever a user downloads an ad. The idea behind ad views assumes the user sees the ad, but there is no reliable way to know whether they have fully downloaded it. Most Web sites prefer to sell ad views to advertisers.
In a spreadsheet, the cell (the point at which a row and column intersect) currently open for data manipulation. The active cell, which can hold text, a numerical value, or a formula, ordinarily is highlighted.
A peripheral (such as a printer or modem) that is not necessary for the operation of a computer but often is useful. Also called accessory.
Refers to a paper’s ability to absorb and keep ink in one place. Papers with very high absorbency may hold ink better, but may lack the vibrant colors produced by papers with lower absorbency.
An expansion board placed in a PC that acts as a TV tuner. The tuner card receives signals from an antenna or cable like any regular TV set. Additional software then lets users change the channels or settings as if operating a television.
A data file is a logical collection of related information stored on a computer's hard drive, tape drive, or other mass storage device. Data files usually contain a specific kind of information, such as a personal music catalog or a contact list. For the purposes of retrieving and processing the information, data files are generally subdivided into data records, which are then subdivided into data fields. Data files are given a meaningful name for the convenience of their human users. This name is stored in a directory, which resides on the same storage device as the file. The directory also stores the disk location of the first part of the file, as well as information, including the date the file was originally created and the date it was last modified. Logically, a data file is a consistent, contiguous collection of information. Physically, however, it is nothing more than one or more blocks of binary data stored on the recording surface of a computer device. On hard drives or other random-access devices, these blocks may be randomly distributed over the surface of the disk and linked together by the FAT (file allocation table) for that device. On sequential devices, such as magnetic tape drives, a data file's blocks must be stored together and in the proper order on the tape due to the slower speed of these devices. Data files may contain fixed- or variable-length records. In either case, the records within a data file each contain similar types of information about different objects. For example, in a personal music catalog, each record would contain similar types of information about a different CD or cassette tape. Each record is subdivided into fields that contain the individual pieces of information for a specific object, such as the title, artist, or genre of a CD. Data files can stand alone or be part of a larger logical scheme called a database. In either case, certain fields within each record are designated as key fields. These key fields are associated with an index file that lets users locate desired records within the data file quickly and easily. For example, the use of an index file would produce a list of all titles belonging to the classical genre much faster than sequentially reading each individual record in the file and discarding those where the genre field is not equal to classical. See database.
The spreading of a signal. In the case of fiber optics, propagation describes the spreading of light rays through an optical fiber.
An MMORPG (such as EverQuest, Asheron’s Call, World of Warcraft, or Ultima Online) lets hundreds of thousands of players worldwide role-play in PSWs (persistent state worlds). Players pay monthly subscription fees to keep the neverending games running on managed servers. As in traditional RPGs, players can develop their characters over time, and gameplay is very open-ended.
A game in which players take on another identity and play the game in an imagined reality. Dungeon & Dragons games are some of the best examples of role-playing games.
When using a search function, a keyword is the word the user wants to find in a document or documents. For example, to find all documents about dogs in a folder, a good keyword might be "dog." Some word processing and database programs let the user attach certain keywords to specific documents to make searching faster; rather than searching the entire file, the search program might only look at lists of user-defined keywords for each file.
A picture-taking mode many digital cameras have that lets users take images that have an overall brownish or bluish tint or impression. Sepia modes are specifically used to give images an antique or aged feel.
A section of the boot drive that contains the computer’s startup files.
A reserved portion of drive or memory that functions as a separate unit; when used as a verb, partition refers to the process of dividing up the space on a drive into smaller units. A partition acts as a separate space, but physically it is still part of the whole drive. A user could, for example, partition a hard drive into several separate drives (such as E:, F:, and G:), while maintaining the physical structure of only one drive. This is a way to make the hard drive more efficient. Hard drives partitioned into multiple sections often work faster because the computer only needs to search a specific section for information rather than the entire drive.
In computer graphics, cropping the part of the image that lies outside a boundary set by the user. Programs that allow screen shots (graphics showing the appearance of the computer screen at the time you take the shot) often let a user clip the image to show only an active window or part of the screen. Depending upon the program, clipping can be done either through a dialog box or by drawing a line around part of the image. Also called scissoring.
A communication method that only allows one participant to transmit at a time. One side sends a message, the line switches from send to receive, and the other side sends a reply.
The disk drive that is automatically employed by an operating system, unless denoted otherwise, when a computer is booted.
A self-contained device, usually in a protective plastic shell. There are several kinds, including ink cartridges, disk cartridges, memory cartridges, and toner cartridges. Also called cart.
A Web site that has remained inactive or has not been updated in a long period of time.
Cooling computer devices with components other than a fan. For example, a heat sink is a passive cooling device. However, many newer processors generate enough heat to require a fan on the heat sink.
A tool found in many image-editing programs that lets the user select a specific portion of an image to manipulate (copy, color, move, enlarge, rotate, etc.) based on a similar color pattern.
A device that routes data between one or more local area networks and an asynchronous transfer mode network. Sometimes called a boundary router.
A secondary menu that appears next to the original menu when an option with a menu of its own is selected. This arrangement is common when a menu item has many related commands. Some cascading menu items have their own cascading menus in turn. This multilayer menu system is where the term cascading came from, as each menu flows from the one before it.
Googlewhacking is the art of trying to find only one Google result on a search with only two words.
A nickname given to software that’s has not yet been released. Beta ware is often distributed to many users before the official release to let them search for any malfunctions.
A type of shareware that interrupts the user while they're using the program and asks the user to register or pay for the software. This usually takes the form of some sort of pop-up box. Usually the user has to click a button before the program will resume.
An angry state of mind in which a computer user may resort to flaming (a personal attack via email) another user. Like road rage, it’s an impulsive action that likely has regrettable consequences.
An email that returns to the sender because the recipient’s address is incorrect or belongs to a recipient the server no longer recognizes. A bounce email usually appears in the form of a message from a system administrator or mail server in the original sender’s inbox with the email in question attached.
An e-mail message that has been directed to the recipient through a third party server and does not identify the sender.
Email that circulates among many Internet users, detailing the latest “scare,” from rumors of terrorist attacks to giant vampire bats. Most turn out to be urban legends.
The opposite of client pull. The server automatically sends data to the clients (usually desktop computers) connected to the server.
Occurs when a desktop computer (the client) initiates a request for some kind of data from another computer. The client computer "pulls" the information it needs from the computer storing the information, usually from a server.
Encoding a file to prevent others from accessing its contents. An encrypted file appears as a string of gibberish. Users must decrypt the file to read or use it. Files are usually encrypted using encryption programs.
A failure by either a computer or its source while in the process of inputting information into the computer.
A portion of memory that temporarily holds data until it can be permanently saved, usually when there is a decrease in a system's activity. This delay improves system performance over that which exists when there are frequent disk writes, because the computer is not constantly pulling data from or storing data to disk. Also called write-behind cache or write cache.
To record a song from an audio CD and encode it into the MP3 format. MP3 files are significantly smaller than audio CD files, therefore ripping them can save quite a bit of space on your hard drive. There are several software programs available that one can use to rip songs from a CD.
The electrical supply needed to operate a computer. Also, the device inside a computer that transforms the AC electrical currents available in a standard wall socket into the lower DC voltages used by a computer.
A designer of computer systems for specific tasks or environments. Systems analysts must consider how end users will use the system before they can design a new unit or add to an existing one. System analysts often can be likened to efficiency experts in that they examine a system to see how it is currently being used and how it is falling short of user needs, demands, and expectations. The analyst then takes this information and creates an effective system that will let end users complete their tasks quickly and efficiently and with fewer problems. After the system has been created, the analyst will supervise its implementation.
To press and quickly release the right button of a mouse or trackball.
To obtain an open channel of communication with a software application or computer component so the user can work with it. For instance, a computer must access an attached modem before it can be used.
The focal length at which the maximum amount of optical zoom is applied.
A prefix meaning one-millionth. Also can be used informally to indicate an object is tiny.
To eliminate unneeded information from a system. Users may purge old files from their computer for more storage space. For example, a student may decide to purge all the document files associated with a history class after the class has been completed.
Performed by a Web browser for quicker access to previously viewed Web pages. Once accessed, the html code along with image, video, and audio files are automatically stored in a temporary file within the browser. When the viewer returns to a page, the browser brings up the site using the downloaded information in the temporary folder. This form of caching also alleviates some of the stress put on Internet connections and servers from large numbers of surfers trying to access a given site.
Networking technologies are plentiful, and keeping them straight is no small task. One of the newer wireless standards is 802.11n. This new standard builds on the previous 802.11 technologies by adding MIMO (multiple input/multiple output) capabilities. The first 802.11n routers officially became available on April 14, 2006. Speeds for these routers can reach speeds in excess of 300Mbps, which is much faster than the currently popular 802.11g standard with 54Mbps speeds.
A word that is reserved for special use in programs and cannot be used for naming files, documents, or macros. Reserved words in certain applications might include operators such as IF, OR, and NOT.
A type of camera that is specifically used to take panoramic images. Panoramic images are those that have a very wide field of view, usually on a horizontal scope. Panoramic images can be just one image or several images stitched together to form a full 360 degrees or less.
A computer display that is sensitive to the touch of a human finger. Touchscreens let users interact with a computer by touching pictures or words on the screen instead of using alternative input methods such as a keyboard or mouse. You’ll often see touchscreens on information kiosks, tablet PCs, smartphones, and PDAs.
An arrangement of information in rows and columns that makes comparing and contrasting easier. For example, charts in newspapers and magazines often are presented in table format.
A way to increase and improve a printer's resolution. Typically, resolution enhancement is accomplished by altering the dpi (dots per square inch). This alters the number of dots that are printed in each square inch of the paper.
A user who is exceptionally knowledgeable and skilled in the use of computers and software.
A return to normal operating conditions after an error has occurred. Recovery may involve complex retrieval of information lost due to system errors.
The amount of computing ability, determined by speed and functionality, a computer has, or the actual electricity used to run a computer.
The ability of a machine to follow instructions and carry out user-dictated jobs. Computers are programmable.
A quality of hardiness; the ability to continue working properly in unusual or difficult situations. In computing, this may refer to hardware's physical durability or software's ability to handle unusual situations without crashing.
The memory controller chip on a specific motherboard and chipset architecture. The northbridge typically directs data traffic between a system’s CPU (central processing unit), graphics controller, and system memory; the bridge is connected to each by a high-speed data bus. A slower, PCI (Peripheral Component Interconnect) bus connects the northbridge to another chip called the southbridge that controls the system’s drives and devices installed to the computer’s expansion slots.
A slang phrase used to refer to a 404 error message. On the Internet, a 404 error means the Internet couldn’t find the Web site requested. Atlanta’s area code is 404.
A measurement for the distance between corresponding peaks or troughs on a transmitted wave signal.
To alter the size of an image. Scaling an image up enlarges it while scaling an image down makes the picture smaller.
Refers to an image taken with a digital camera that is framed vertically, or so the scene spreads out up and down. A landscape image differs in that the image is framed horizontally, or so the scene spreads out from side to side.
Keys that act as shortcuts for performing functions such as saving files or printing data. Function keys are usually lined along the top of the keyboard and labeled F1 through F12, although some keyboards have fewer and others have more. Function keys also might be on either side of the lettered keys along the right or left edge of the keyboard. Function keys change their function depending upon which software is running, although the F1 key, for instance, often brings up a help screen.
To damage an electronic component by letting too much electrical current pass through it.
A play on the term war dialing. War driving refers to the hobby or outright obsession of driving around a neighborhood in an attempt to locate wireless Internet access points.
A type of hard drive space that mimics actual memory (RAM). When actual memory space is limited, the use of virtual memory can let users work with larger documents and run more software at once. When a program needs information held in virtual memory addresses, the information is moved to actual memory addresses. This process of moving sets of virtual addresses (or pages) into actual memory is known as paging or swapping. When virtual memory is used, it appears to the user as if actual memory is in use. The process may be a bit slower, however, because of the time required to swap information between virtual and actual memory.
To temporarily place a function or application on hold without shutting it down. Users can then pick up the application where they left off.
A slight, slow, wandering movement of objects on-screen that are supposed to remain fixed.
An electrical component that provides resistance to a flow of electrons. Used in electrical circuitry for protection and to control a current.
A cable that’s enclosed by one or more layers of a conducting polymer, which redirects electrical noise away from the cable’s internal wire. The shielding prevents electromagnetic radiation from interfering with the signal passing through the cable.
A function available in some digital cameras where the user can identify specific images to be stitched together within the camera to form a single panoramic image. Panoramic images cover a very wide field of view, usually on a horizontal plain.
A data transmission mode in which information is sent one character at a time.
To begin a program or use a program.
In Windows, a restore point refers to the point at which a system was backed up. If a system change causes a problem, you can restore the system to the last working restore point.
To change the size of a graphical element. Often refers specifically to changing the size of a window in a graphical user interface.
The information about the activity level of an aspect of the computer system such as a device or a program. For example, the flashing light on a diskette drive indicates that the status of the drive is active.
The PC receiving data from software, another PC on the network, or a communications device.
To eliminate data from a storage medium, this leaves the medium available for future storage.
Artificial life models complex behaviors in software. Artificial life can learn new behaviors not defined in its software.
Computers or applications that work with data 32 bits at a time. A 32-bit computer might have a microprocessor capable of handling 32 bits of information at a time. More commonly, 32-bit also can describe the capability of the computer's bus to transport 32 bits of data at a time. Most computers based upon Intel's 80386 microprocessor are 32-bit machines. A 32-bit operating system such as OS/2 Warp and recent versions of Windows works with information in 32-bit groups.
A hard drive in a plastic or metal cartridge that can be used and removed in a manner similar to a diskette. A major benefit of this type of hard drive is that it can be moved from one computer to another if both machines have a bay to accommodate the removable hard drive. This lets large applications and documents be moved from one location to another.
A type of logic bomb (destructive programming code) that is triggered when the clock reaches a predetermined time. A time bomb can wreak havoc on a software system.
Technology without an interesting name.
(Pronounced “leeds”) The metal pins or legs of an integrated circuit chip (including microprocessors).
In graphics programs, when a user grabs one portion of a line or image and moves it while other parts stay anchored, causing the line or image to stretch.
A method of increasing or decreasing the playback speed of an audio recording without altering the pitch of the recording.
A fake computer virus warning, typically forwarded by someone using a distribution list. If you receive such a warning, you may want to investigate the claim by checking one of the numerous sites that keep current lists of active viruses and worms.
A keyword or character set used to arrange information into a desired order.
The trim feature of many software programs lets you cut out unneeded parts of an image. In many programs, this feature is called the crop tool.
A mode that prohibits the OS (operating system) from interfering with the direct flow of bits to or from an I/O (input/output).
Word-of-mouse is a term that describes the spread of information, accurate or otherwise, via email.
Slang for items that adorn a person’s computer monitor.
A feature of some applications that automatically records, at periodic intervals, changes made to a file. The changes are saved to a temporary file that can be retrieved. Autosave helps prevent accidental data loss.
A bit-mapped graphic that appears as a backdrop on the Windows desktop and other operating environments. In Windows 3.x, wallpaper is controlled from the Windows' Desktop icon in the Control Panel. Wallpaper images can be basic images (such as the Windows logo) or patterns (such as argyle or tartan) to more elaborate photographs, cartoons, or other images created by users or provided by third-party manufacturers. Also called backdrop.
A special chemical coating on a monitor’s glass that reduces static electricity and dust buildup on the display. Most monitors come with antistatic coating.
An add-on device made from polarized material that can be placed in front of a monitor's screen to reduce glare and prevent eyestrain.
Strategies used by some Web marketers and hosts as a way of keeping their services at the top of search engine results. Spamdexing includes submitting multiple, yet slightly altered, Web sites to a search engine, and "word stuffing," which places a word or keywords in a site numerous times, to ensure the search engine will bring up the site as one of the top keyword matches. Other techniques include "bait-and-switch" gimmicks, such as loading the site with frequently used keywords such as "free,""sex," "money," or "shareware," even though the words have nothing to do with actual site content.
The equivalent of unsolicited email that is sent to VoIP (Voice over Internet Protocol) voicemail boxes.
A spam message in your email account that contains predictions of high performance for a specific stock. The email scam relies on spam recipients to buy the stock and increase the stock price. Once the stock price increases, those who sent the spam will sell their stock for a profit, which they purchased for a low price before sending out the pump-and-dump spam.
Software that monitors a computer for viruses by looking for irregularities in a computer system and then comparing its findings to a database of virus information. Viruses not included in the antivirus program's database will go undetected, so it is important to periodically update antivirus programs with information about new viruses. Such updates usually can be purchased on a subscription basis from the company that produced the antivirus program. The regular use of an antivirus program often can eliminate a virus before any damage is caused. Antivirus applications should be used when foreign software is introduced into a computer.
The area of a printed page actually covered with toner. The industry assumes an average of 5% toner coverage per page to gauge the number of pages a toner cartridge can produce.
A device that takes commands from a computer and produces hard copies, usually on paper, of the text and graphics that appear on the monitor. Printers such as the daisywheel and dot matrix produce images by striking the paper. Inkjet, thermal, and laser printers use more complicated and precise methods to render characters and images. These printers generally produce a higher-quality image than daisywheel and dot matrix printers.
An intensely focused beam of light. Lasers have many uses, from reading stored optical data (such as on CD-ROMs) to high-quality printing (laser printers). Laser is an acronym for Light Amplification by Stimulated Emission of Radiation.
When printing a document or image on a laser printer, the paper is rolled between this extremely hot roller, which is kept warm with an internal halogen lamp, and a pressure roller to melt the toner and create the image. In color printers, two fuser rollers are used to melt the toner.
The hallucinatory, mesmerizing image displays that many music programs display as songs play on your PC. If you use Windows Media Player, you can download new visualizations from the Internet.
A single button on the keyboard. Letters, numbers, and symbols are all represented by keys on most keyboards, along with several special function keys (for examples, see the CTRL key and the ALT key). Pressing a key in many applications causes the character on the key to display on the monitor. Also refers to the code used to encrypt and decrypt data. There is also sometimes a physical key that can lock a system.
If something is static, it is unchanging. In computers, static is often opposed to dynamic. For instance, a static IP (Internet Protocol) address is a constant IP address often used for Internet servers while a dynamic IP address is an IP address that changes regularly.
The ads you see on most Web sites aren’t permanent. Instead, many sites have a list of different ads that they rotate onto the site.
Two depressions of the mouse button, performed rapidly and without moving the mouse. Double-clicking is one method of opening an application in graphical user interfaces (GUIs) and also can be used to activate commands.
A standard element of graphical user interfaces (GUIs) in which one option is presented along with a small button, usually represented by a downward-facing arrow. Clicking the arrow with the mouse causes a list of other options to appear below the first. The user then can select from the options by clicking one. The drop-down list then disappears, leaving the selected option displayed in the original box next to the arrow button.
The reliance of one program, operation, or device upon another for its function.
A more friendly variant of spam, bacon (also called bacn) is a term used to describe email you signed up to receive from a Web site you know and trust. These emails can be notices of software updates, new product notices, or information about podcast schedules. Not quite personal mail, these messages sometimes go unread.
To find a piece of data and bring it to an active application. Information can be retrieved from memory or a storage medium, such as a diskette.
A method of copying the contents of a computer's entire hard disk to a file. The file can then be placed onto the hard disk of another computer, creating a system with the identical software and settings as the first. This is a simple way to set up several systems with identical configurations.
A central repository for a user’s voice mail, e-mail, faxes, and other messages that the user can access either by phone or PC. UM is an example of CTI (computer-telephony integration). It has given way to the broader concept of UC (unified communications).
In every Windows OS (operating system) since Windows 95, the far right end of the Taskbar, in the bottom right of the screen. The System Tray displays the time as well as the status of various Windows functions. You can also change some system configurations via the System Tray, such as the volume. Various software programs, from virus scanners to RealPlayer, might place an icon in the System Tray that lets you conveniently launch the program and change the program's settings.
A computerized imitation of a real object or action.
Programming jargon for checking software code for blatant errors.
The menu that appears when a user clicks the Start button. The Start menu gives the user access to all programs on the computer, unless the user has instructed it otherwise.
A video card that contains a graphics coprocessor designed to handle graphical computations better than the computer's CPU (central processing unit). The coprocessor increases the speed of on-screen images and improves system performance by relieving the CPU of the graphical tasks, letting it handle other tasks. The amount of RAM (random-access memory, either DRAM [dynamic RAM] or VRAM [video RAM]) contained on the video accelerator, which has become standard equipment on most new PCs, determines how many colors and which resolutions are possible on the system. Also called a graphics accelerator.
A term used with industrial-strength items. For example, a Rackmount Chassis, Rackmount Keyboard or Rackmount Console. Describes how the piece of equipment is made; it comes ready to be attached or mounted to a rack or another piece of equipment.
The integration of hardware and software to create a machine, such as a computer, that can perform work. System can refer to a single computer or a system of multiple computers. Also can mean an operating system.
Sometimes called a “nibble” in the communications industry, a quadbit is a 4-bit combination used to carry encoded transmission signals. This allows for more efficient data transfer, because the signal doesn’t have to be carried one bit at a time, but in groups of four.
Recognizable and memorable domain names that include words or combinations of words that relate to the person or organization that owns the domain. Most domain names are vanity domains.
A request for data not found in cache memory. When this occurs, the computer must search the main memory to find the data.
To render a computer, application, or other resource inactive without removing the item from the system. In this way, technicians can reactivate the resource much more quickly than they could if they had to reinstall it.
The part of the printer that determines the resolution, speed, and overall quality of the printing. Most engines are replaceable self-contained units; printers from different manufacturers often use the same engine.
Repeating a word on a Web page in an attempt to increase its relevancy when people perform a Web search. This attempt is usually in vain, as search engines typically locate information using methods other than a simple word search.
The ability to update data, such as a number in a spreadsheet cell, when it is being displayed in a different application, such as a chart or a graph. This lets the user change the data in the originating application and see the results in other applications that use the same data.
Speed dial refers to the ability of a telephone or cell phone to store a given telephone number in its internal memory. With a speed dial-enabled phone, a user can assign frequently dialed numbers to a short button sequence or to dedicated speed dial buttons and then press these buttons to quickly call that number.
Physical topology is the placement of hardware on a LAN (local-area network). This is where the connections are set up and the location of cables, switches, etc.
A section of an overall network (either LAN [local-area network] or WAN [wide-area network]) specifically reserved for storing data. SANs consist almost entirely of storage hardware. Servers connected to the network are gateways to the SAN subnetwork, where information can be stored and accessed.
One of the main input devices used by computers, a PC's keyboard looks very similar to the keyboards of electric typewriters. Computer keyboards, however, usually include extra keys such as the function keys, cursor keys, and a number pad.
A menu item in most programs that provides electronic assistance. Textbook-like help is available for searching and may be context-sensitive, meaning the help may change according to the type of function or program users are working on when they select the help option. Although most help files are usually portions of the manual put on-screen, some help options also may include tutorials and tips on how to use the program.
An input device used with computer games, typically with flight simulation games, that allows the user to fly up or down, back or forward by pulling or pushing the steering wheel-like device.
Random-access memory gives a computer a fast storage area for the programs you run. Without enough RAM, the computer feels sluggish because it has to use the hard drive instead. A new system should have at least 2GB of RAM. If your computer runs Windows Vista, however, you should consider 3GB or even 4GB.
The information category that a sort process uses to organize the database information. For example, "last name" might be a sort field.
A term used to describe 100Mbps (megabits per second) Fast Ethernet network segments that use fiber optic cable rather than twisted-pair wire and support full duplex (the simultaneous sending and receiving of data) transmission. The IEEE (Institute of Electrical and Electronic Engineers) standard that includes 100Base-FX standards is 802.3u.
A play on the word “tradition” that means the passing down of technology-related information, through word of mouth, in digital documents, and by other means.
A blinking horizontal or vertical line or a square that denotes where new characters or changes will appear in a text field.
A list of image quality adjustments on the screen accessible by controls on a monitor's bezel.
An email that a user receives by requesting information that comes on a regular basis from a Web site. Newsletters and notification of changes to a Web site are examples of opt-in emails.
The set of standards that let users of the Web exchange information found in Web pages. You can use a Web browser, such as Microsoft Internet Explorer or Netscape Navigator, to read documents formatted and delivered according to HTTP. The beginning of every Web address, "http://," tells the browser the address' document is HTTP-compatible.
A menu in a graphical user interface that is opened by placing the screen cursor over the title and clicking a mouse button. A list appears below the title, and the user can select options from that list.
A malicious or nuisance program embedded within an html (Hypertext Markup Language) file, email attachment, or push technology data. Vandals often arrive in applets or ActiveX controls and, unlike viruses, do not self-replicate. They can, however, breach security restrictions within a computer to access passwords or cause loss of service for users within a network.
A high-capacity optical storage format similar to DVD. Blu-ray was developed by the Blu-ray Disc Association, a group of developers that includes Sony, Philips, Apple, Dell, Samsung, and Mitsubishi, as well as many others. Blu-ray takes its name from the blue-violet color of the laser used in a Blu-ray player or PC drive. CD and DVD players and drives use red lasers. A Blu-ray player’s laser beam is thinner and more tightly focuses than the laser of a DVD player, so manufacturers can store more bits of data much more closely together on a Blu-ray disc than they can on a DVD. Blu-ray is designed to use high-definition video and audio and may replace video DVDs. Blu-ray video players can play video at resolutions up to 1080p, a higher-quality resolution than DVD players can produce. PC users can also record large volumes of data to a recordable Blu-ray disc, assuming a user has a Blu-ray recordable drive. A single-sided, single-layer DVD can store about 4GB of data, but a single-layer Blu-ray disc can store 25GB of data. A double-layered Blu-ray disc can store 50GB of data. Blu-ray supports the MPEG-2, MPEG-4 AVC, and SMPTE VC-1 video formats. It also supports several audio formats, such as linear PCM, Dolby Digital, Dolby Digital Surround, Dolby Digital Plus, Dolby TrueHD, and DTS Digital Surround.
A program that has a tendency to stack its dialog boxes on top of one another, which may make it difficult to use the program properly.
A portable computer battery that keeps its system up-to-date about its power status. Also called an intelligent battery.
A one-time pad is a cryptography term used to describe a process in which a message is encrypted using a randomly generated key. A unique key is randomly generated for each encrypted message. To decrypt the message, a recipient must have the same key. Theoretically, one-time pad encryption is impossible to break because each key is unrelated to other keys. However, working on a secure method to transmit the secret key to the receiver is a problem. Generally, one-time pad encrpytion takes place when both the sender and receiver begin at the same physical location and then separate. This technique was commonly used in WWII.
A notebook less than four pounds. In many cases, mininotebooks come in a smaller package, meaning you have a smaller display. Power is an issue because there’s not as much room to add a large power source to a mininotebook. Smaller displays help conserve power as do slower processors and graphics controls. Mininotebooks are typically one-spindle devices capable of supporting only a hard drive. You can add an optical drive and/or floppy drive by clipping additional hardware to the bottom of the notebook or attaching the drives with cables (to USB [Universal Serial Bus] ports, for instance).
Any component installed in or connected to a computer that expands the capabilities of the entire system. Modems and printers are two examples.
A popular solid-state flash memory module used in MP3 players, digital cameras, and other gadgets. SmartMedia cards are very thin at 0.03 inches and are 1.46 inches wide by 1.77 inches long, with a notch on one corner. This format also is known as the SSFDC (Solid State Floppy Disk Card) because it can fit inside an adapter that slides into a PC’s diskette drive. Occasionally the term SM card is abbreviated as SMC (SmartMedia card).
A number indicating how far from a starting point an item is located, usually in bytes. For example, an offset might tell a processor how many bytes into a segment of memory it will find a specific piece of data. This is the computing equivalent of giving directions to a house by saying it is the second one from the corner; it gives a reference point and counts from that point to the desired item.
To take a document, break it down into separate pages, and number the individual pages for printing.
A reference to fiber optic cable that has been installed but is not yet in use. Companies sometimes install extra cable when setting up a fiber optic network in anticipation of future needs.
Internesia is a slang term that describes the inability to remember where you found a key piece of information. It’s obviously a combination of the words Internet and amnesia.
A measurement a Web publisher takes to count the number of times it delivered an ad. The server's log files, or records detailing its activity, count the number of times the server sent a Web page with a specific ad on it to a user. Impressions do not consider whether the Web surfer actually saw the advertisement, just whether the surfer had the opportunity to see it.
Text messages sent through a network to a specified individual or group. Received messages are stored in an Inbox and can be kept, deleted, replied to, or forwarded to another recipient, depending upon the email program. Besides a message, an email may have an attached file or graphic. Users can make sure a message was received by requesting a receipt. Although not all items can be sent electronically, email's big advantage over postal mail, nicknamed "snail mail," is speed. Email can be delivered within seconds or minutes across thousands of miles. May also be spelled e-mail or E-mail.
Computers or applications that work with data 64 bits at a time. A 64-bit computer might have a microprocessor capable of handling 64 bits of information at a time. More commonly, 64-bit also can describe the capability of the computer's bus to transport 64 bits of data at a time.
Video playback in which individual frames are changed at a rate of at least 30 frames per second (fps). On a computer, video can play at various frame speeds depending upon system resources. At slower than 30fps, the image begins to appear choppy and not fluid to the human eye.
A device, such as a hard drive or sound card, that may have been intended for inclusion in a system package but for whatever reason has been repackaged to be sold separately. White box refers to the cardboard packaging the device comes in, although the packaging is often not a white box at all. The devices themselves are often referred to as white box devices.
Huge, vertically-oriented banner ads along one side of a Web site.
A term used to describe the method of scanning the odd numbered horizontal lines making up a picture on a CRT (cathode-ray tube) monitor before then scanning the even numbered lines. This method is sometimes used when a monitor’s resolution setting is above 800 x 600 pixels per inch in order to help reduce screen flicker.
A twist in an image that makes it look tilted to one side or another. Some image-editing programs have a skew feature to help users warp their images.
An uplink is a connection from a ground-based transmitter to a satellite. The satellite can then relay the signal to a ground-based receiver over the downlink connection.
An air card is a small card that connects to your laptop or mobile phone and gives you wireless Internet access. It does not replace the Wi-Fi capabilities of your mobile devices; rather, it augments the availability of wireless Internet. Air cards connect to mobile devices through PCMCIA (Personal Computer Memory Card International Association), ExpressCard, or PC Card Type II slots, though some models use a USB connection. After you install the accompanying software, your card should be ready to use.
If you're the type of person who likes to work outside of the home or office, an air card may be just the thing you need to beef up your productivity. For example, if you'd rather spend an hour returning emails in the park instead of a coffee shop, you can just pop your air card into your laptop and have at it.
A special ability of some printers whereby the printer only needs the outline of a particular font to create it in any required size.
The approximate number of commands carried out in one second. Microprocessor power is sometimes measured in MIPS as a way of comparing chips. This practice is somewhat controversial, as some computers require a different number of instructions to complete the same task.
A graphical special effect that produces a 3D color look. A gradient fill uses a gradual blend from a light background to a solid foreground or from one color to another.
A circuit board that survives after power is applied is said to have passed the smoke test. A short circuit or some other problem may result in a smoking circuit board.
Phishing is the act of trying to trick users into giving up personal information by making them think they’re dealing with a legitimate business. A phisher sends unsolicited bulk emails to a large number of users. The email claims to be from a legitimate company, such as AOL or eBay, and claims the user’s account will be suspended unless they click on the provided URL and supply the requested information (often passwords, credit card numbers, and other personal information). The URL is on a server controlled by the phisher, but its appearance is similar to that of the real site.
A noncommercial, often personal page that updates its content once a day or more and typically focuses on a specific subject, topic, or theme. Web logs usually feature updated content from the site creator, viewers, and/or other Web sites as well as moderated discussions about a variety of subjects.
The unit for measuring electrical current; current measures the amount of electric charge flowing through a conductor at a given time. An ampere is the charge of one coulomb (a unit of electric charge equal to 6.25 X 10 to the 18th electrons) passing a point in one second.
The bar located along the top of a window or dialog box that displays the application's name. In Windows 3.x, the Control menu box, minimize button, and maximize button are located on either side of the title bar. In Windows 95 and subsequent Windows OSes, the title bar includes the minimize button, the maximize button, and the close button.
To organize data. For example, the information in a database can be sorted alphabetically, numerically, by keywords, and in other ways.
One occurrence of a repeating event.
The image or text viewed on a monitor. More recently, display has become synonymous with the monitor itself, particularly when referring to flat panel displays.
Short for pseudonym, a word used to describe the name given to or created by a computer user for the purpose of keeping that user’s real identity hidden. Nyms are used to conceal identities when sending and receiving email and browsing the Internet. When you pick or are assigned a nym from a privacy company, all your incoming and outgoing email and Internet browsing requests go through the company’s servers and are processed under your nym. Anyone looking for your identity, then, will only be able to know you by that chosen or assigned name.
The specific light-sensitive area on an image sensor used to capture a digital image. Most image sensors used in digital cameras are CCDs (charge-coupled devices) or CMOS (complementary metal-oxide semiconductorsS). Other portions of an image sensor are used for other purposes.
The file format used by Intuit software to store financial data. A .QIF file can be imported into programs such as Intuit Quicken or Microsoft Money.
The most basic computer language used by the computer's processor to communicate with the rest of the system when no other language has been introduced to the computer. In most cases, the native language is the binary code inherent to the processor before the OS (operating system) has been introduced.
A do over; in documents, this means to reword or edit sentences, paragraphs, and pages. In data storage, rewrite means to save over a file with the same file.
Advanced cellular phones that can also receive text and data via the Internet.
When looking at specifications for new software, be aware that manufacturers will often list minimum system requirements as well as recommended ones. Though the software may work with the minimum requirements, it's probably a good idea to make sure that your system has the recommended ones because the programs you install will generally run a lot smoother and crash less if your system doesn't have to use every bit of its resources just to load them.
A list of information about files or storage space. File details might include name, length, type, and location. In a database, catalog refers to the data dictionary.
A cache made of high-speed SRAM (static RAM) linked directly to the CPU. RAM caches are used for keeping a copy of the most recently and most frequently accessed data in memory so the information is more quickly accessible. Also called a memory cache or processor cache.
An antenna or other device used to connect one network to another network over distances without cables or wires. A wireless bridge, for instance, could connect networks in multiple buildings on a college or company campus. In other circumstances, a wireless bridge could connect an office network in one part of the city to an office network in another part of the city. In order for a wireless bridge to work, both nodes must have a clear line of sight path to one another. Wireless bridges can be omnidirectional, meaning they radiate a signal in all directions, or directional. Directional wireless bridges must be pointed directly at one another.
The various definitions of a PC's ability to display colors and resolution. A PC supports a certain video standard only if both the monitor and the video adapter support the standard. The numbers specified for a standard often are minimums; many manufacturers claiming to meet that standard actually exceed the minimum numbers.
A peripheral that is limited by the boundaries of an on-screen application window as it manipulates the movement of a cursor.
A method of ordering data that accounts for alphabetic order, punctuation, and numerals. It often organizes data in the following order: punctuation marks, numbers, capital alphabetic characters, lowercase alphabetic characters, and any remaining characters.
Computer hardware or software that works with older versions or standards. Backward compatibility is popular because it lets users upgrade systems and software gradually, rather than starting over from scratch each time a new version or standard is released.
In Windows-based applications, an option that, when activated, identifies the registered user of the program, the version number, and the program's creator. The About command usually is located in the Help menu.
A plate found on a scanner or copier that the document is placed on to be scanned or copied. The glass allows light to illuminate the print on the document so that it can be processed.
To record information on top of previously recorded information, replacing the old with the new.
A type of rack-mounted server that can accept additional motherboards, called server blades, each of which has its own CPU, RAM, and associated circuitry. The blades share a common power supply, operating system, and management mechanism. The blade-style server's modular approach to adding processing power reduces the overall cost, heat output, size, and management difficulty of a group of servers, especially compared to a traditional server farm of similar power.
Used to describe times when network activity is at a minimum. Off-peak hours typically include evenings and weekends. Mobile phone companies often provide a greater amount of free off-peak minutes than peak minutes and may charge less for additional off-peak minutes compared to peak minutes. Off-peak can also describe the hours at which Internet traffic is at a minimum.
GUI is a program interface that incorporates the computer’s graphic capabilities into the application, which makes it easier to use. A good example of a GUI is any Windows operating system. The user interacts with Windows through icons, windows, menus, and pointers as opposed to typing in DOS commands.
A land is the smooth part of the underside of a CD-ROM, as opposed to a pit, which is an indentation on the underside of a CD-ROM. When the laser from a CD drive passes over a land, more light is reflected back to the photo cell than when the laser passes over a pit. This is how a CD drive distinguishes between pits and lands. The pits and lands equal the ones and zeros that make up the binary language of computing.
A clear window in a computer's tower case, usually in the case's removable side panel. Case windows are most often found in high performance desktop systems and are intended to show off the components inside. Case windows are typically made of scratch-resistant acrylic.
Located on a circuit board; sometimes meaning specifically on the motherboard. For example, memory chips on the motherboard are referred to as onboard memory.
The insertion of tiny blank spaces between words, performed by a word processing application when justifying text.
A technique used to create more realistic looking objects in three-dimensional (3-D) applications by giving them a detailed texture. Tree bark, for example, would be very detailed to give the tree a rough appearance.
Audio compression software uses two types of compression, lossless and lossy, to create smaller digital music files. Lossless compression retains the quality of the original audio recording. All of the 1s and 0s in the audio track are accounted for, and all of them are re-created perfectly when the compressed music is decoded. That means there is absolutely no quality loss compared to the original audio file, but lossless compression is extremely inefficient. It generally crunches files down to half their original size, meaning that with lossless compression, a 74-minute CD will consume about 325MB of space on your hard drive. Lossy compression gives up some quality to achieve much smaller file sizes than lossless compression. Lossy formats use different algorithms to strip some of the frequencies and other data out of a song that don't necessarily make any difference to our ears. A track compressed using a lossy algorithm may not have the dynamic range of the original track and may not sound quite as crisp, but it's possible to create perfectly acceptable music using a bit rate as low as 128Kbps for most types of audio. Audio that doesn't have a lot of dynamic range, such as audio books, can be recorded at bit rates as low as 64Kbps and remain virtually indistinguishable from the original audio CD. Using lossless compression, you could fit more than two hours worth of perfect audio on a single CD. Not bad, but using a bit rate of 128Kbps, you can squeeze more than 10 hours' worth of music on a CD or 20 hours' worth of audio books recorded at 64Kbps.
A computer model of a 3-D object, using wires to define the outside edges of the object. The wireframe provides the skeleton of objects rendered in 3-D for programs such as games.
A separate browser window that “pops up” when a user enters a certain Web site. Interstitials are usually advertisements, and they often include animated content or other graphics. The user can then click these ads or graphics to link to Web pages with more information. Some interstitials go away after a few seconds, but most must be closed by clicking the close buttons in the upper-left corner of the window. Also called pop-up ads.
A tool included in many photo-editing programs that simulates a spray paint pattern on a photo. Typically the user can define the color and size of the spray. Airbrushing is also a term often used by people who make a hobby of modifying their PCs. These users pay artists to airbrush complex (and expensive) artwork onto the side of their PC cases.
The organization responsible for writing the official definition of open source. It exists to promote the use of open-source software and to convince businesses to open-source their projects. While the OSI is actively involved in open-source advocacy, it is not opposed to proprietary software.
An amount of time in which a process runs without interruption. Also known as a time slice.
Usually used in reference to video services or video downloads. On-demand refers to a user’s ability to access, download, or view content at the time of his choosing, rather than at a predetermined time, as with a television show. Many cable services are now offering on-demand video services, and some online media portals, such as iTunes, are now offering video downloads and streaming video of television programs. Some hardware products, such as Tivo and other DVRs (digital video recorders) are also providing a sort of on-demand service in that they record TV shows and movies for the user so she can watch them at her convenience. Other devices, such as the Slingbox, let users view their local television programming from anywhere in the world, so long as they have access to the Internet.
An individual or company that creates or delivers content, usually through the Internet, although it can also refer to those who provide content for cell phone users. "Content" may be in the form of text, audio, video, or images.
The printed circuit board that is the foundation of a computer. This board contains a computer's CPU (central processing unit), RAM (random-access memory) chips, and expansion slots. The motherboard is where all of the computer's components meet. Also called system board or mainboard.
The size of a device, in physical terms rather than capacity. It can be used to describe media sizes (such as 3.5-inch and 5.25-inch diskette drives), but is more often used to describe the size and layout of devices' cases. A form factor for a computer case or motherboard describes its dimensions as well as its layout, such as the location of hard drives, CD-ROM and diskette drives, slots, and ports. Form factors for computer cases and motherboards can have descriptive names, such as the Baby AT form factor for motherboards.
A drive that sits within the computer’s case.
A biometric technique that compares the size, shape, and features of the human hand for purposes of verification. Although the human hand is not unique enough to be used for identification on its own, it can be used to verify a person’s identity in concert with a PIN number, fingerprint, or some other means of identification. When users place a hand on a hand geometry device, a computer captures an image of the hand and compares overall size, width, and length and curvature of the fingers to previously captured information.
Certain versions of Microsoft’s Office affix a GUID to all documents it creates. The GUID can be used to trace a document back to a specific computer (and therefore, a specific user). A number of privacy concerns involving the GUID have been raised by individuals who fear GUIDs could be used to track down individuals who want to speak anonymously.
A character, such as a period, that isn't valid or can't be used in certain commands because the character is used for some other reason within the operating system.
An ICE (in-circuit emulator) is a computer chip used in the design of embedded systems. An ICE emulates the embedded processor used to run the system and allows developers to design and debug software.
A temporary storage area in a computer's memory, usually RAM, that holds recent changes to files and other information to be written later to the hard drive. Because hard drives are relatively slow compared to RAM, buffers speed up performance. However, buffers generally are wiped clean by power outages; saving a file moves the information to the hard drive. Print buffers allow printing in the background while the user moves to another application or document. Buffers also are used by some transmission protocols. Incoming data might be stored in a buffer until they are verified.
If your external storage device shows up in My Computer, but you can't access or write to the drive, the drive may be incorrectly formatted for Windows or have a corrupt partition. Windows 2000 and XP feature a utility called Disk Management that analyzes your external drive and assigns it an Online, Healthy, or Unreadable status. Open the utility by right-clicking the My Computer icon and selecting Manage. Under the Storage heading, double-click Disk Management to view your external storage drive's status. If it has an Unreadable status, you need to format the drive to remove the corrupt partition or incompatible Windows file format. Before you do, attempt to transfer the drive's data onto another computer because formatting completely erases the files on the drive. To format, simply right-click the external hard drive and click Format.
A slow-moving mail server designed to trap and punish address harvesters. A spammer's mailer gets stuck when she tries to send spam to email addresses gained from a teergrube host.
A peripheral device that captures photos, graphics, or text, and converts that data into a digital format for editing on and output from a computer. Some scanners, coupled with an OCR (optical character recognition) program, can scan blocks of text into a word processor for editing, while others are designed specifically for photos, slides, or film. Scanners come in many shapes and sizes. Some of the most popular types of scanners include flatbed, sheetfed, handheld, and film.
A program that "crawls" across the World Wide Web, automatically collecting Web pages. Most spiders will follow every link on a page, cataloging each page, until it comes to a dead end. Then it will start over on a new page. Spiders are used primarily by Web search engines to gather data for the search engine's database. Search engines don't actually search the entire Internet when a user enters a search term. Instead, they look at the database of Web pages collected by their spider. Spiders are also known as crawlers and bots.
In terms of fiber optics, the jacket is the outermost layer of a fiber optic cable made of hard plastic. Its purpose is to protect the cable from moisture, scratches, and other elements. The jacket is one of several protective layers that make up an optical cable.
If you don't have one already, consider investing in a UPS (Uninterruptable Power Supply). A UPS protects your computer by providing battery power after a power outage or electrical surge. This enables you to save your work and shut down your system safely. Suitable for home use, a standby UPS uses utility power under normal circumstances, but when that power is interrupted, it will use a backup battery. A continuous UPS will run off constant battery power. Depending on how many devices you have connected to the UPS, battery power can last approximately 15 minutes or longer. There are UPS's built to sustain power for longer amounts of time.
Equal to exactly 1,024 bits. Used to measure data storage or transmission in terms of bits, as in kilobits per second (Kbps).
Hotspots are locations that provide wireless Internet service via a wireless access point. Hotspots are usually in populated public areas, such as a town square or downtown area, as well as at hotels and airports. In some instances, users may have to pay for access whereas other hotspots provide free access.
Podcasts are downloadable episodes of programs that are similar to radio broadcasts. These files are saved in a compressed audio format, such as MP3. Users can download individual episodes of favorite programs, or they can subscribe to podcasts. Typically, podcasts are delivered to subscribers through RSS (Really Simple Syndication) feeds. Podcasting is a method of publishing files to the Internet, allowing users to subscribe to a feed and receive new files automatically by subscription.
A function on many printers that allows the characters to be formed with as few dots or as little ink or toner as possible. Despite its substandard quality, draft mode is used for rough drafts because it is quicker and more economical than the normal printing mode.
Reducing a window to a small button or icon, while keeping the application running inside it open. In the newest Windows operating systems, the minimize button is in the upper right of the application and has a short horizontal line at the bottom. When you minimize an application, it appears in the Taskbar as a button that, if clicked, maximizes the application.
A term used by programmers to describe the amount of memory a program needs in order for it to work. Heap memory has been set aside for a program to request as needed to operate. A set amount of heap memory is hard to determine before a program is started because the amount changes as a program runs.
One of two kinds of clocks in most computers. The first is a real-time clock, which keeps track of time just like a wall clock or wristwatch and often includes the date. This clock usually is battery-operated, so it continues working when the computer is turned off. The second kind is the system clock, which actually is a circuit that generates a series of pulses that pace the electronic system within the computer, synchronizing the circuits and operations.
A detailed list of a system's or application's activities. A log can be useful for keeping track of computer use and emergency recovery of data.
The act of manually creating a page break in a document. Word processors typically mark page breaks automatically, but you have the option of creating a page break at any point in a document. The text following the hard page break will appear on the next page.
Any surface on which a mouse is used. Normally, this would be a mouse pad. However, because optical mice function on most surfaces, common mousing surfaces today also include desktops, stacks of paper, and even pant legs.
Full-motion video represented by the 0’s and 1’s of the binary system. Digital video is a bandwidth-intensive function, meaning you need a capable multimedia PC to handle its demands.
Bluetooth is a wireless standard that takes advantage of short ranges and slow data transfer speeds. You'll find Bluetooth-capable PDAs, game controllers, wireless headphones, printers, and digital cameras.
Bluetooth is extremely secure due to its multiple layers of data encryption. Typically, Bluetooth-compatible devices will require a PIN and Bluetooth address to identify other Bluetooth devices. A low-powered Bluetooth device can transmit up to 30 feet and a high-powered device up to 300 feet.
USB (Universal Serial Bus) flash drives are high-speed, high-capacity memory devices designed for long-term data storage and easy transport among PCs. The host PC treats the device just like a drive, so you can transfer files of all types to and from the device. Because the device emulates a drive, it supports any type of file, including audio files (such as MP3s) and graphics files (such as JPEGs [Joint Photographic Experts Group] and BMPs [bit map]). In addition, USB flash drives can easily support applications, CAD (computer-aided design) drawings, and a wealth of personal information you’d rather not leave on any particular PC. Most USB flash drives are smaller than a pack of gum and can easily fit onto a key ring. A flash drive is also called a thumb drive or travel drive.
As a verb, integrate refers to the action of two or more hardware or software components working together as a system. As an adjective, it means something is a single, conglomerated unit.
A dual-core processor has two execution cores on a single chip. Each core independently accesses the frontside (system) bus, which connects the CPU to the system's RAM.
A dual-core processor is ideal for multitasking—for instance, watching streaming video while listening to MP3s with other applications open, as well—or playing graphics-intensive games.
A printed circuit board connected to the motherboard at an expansion slot. An adapter card enables a computer to communicate with a peripheral. For example, a joystick requires an adapter card to communicate with the computer system. Also called controller card.
An automated program, generally in the context of the Internet. These programs either gather information or perform a task for you without your intervention. An example would be services that check to see if specified Web pages have been updated. Agents include "bots," which can, for example, be set to gather news items of interest.
For power-hungry laptops and portable DVD players, an external rechargeable battery is the only type of portable power that stores enough energy to provide the extra hours of battery life you need on a long plane ride. The additional usage time you'll receive from an external rechargeable battery will differ depending on the watts stored in the battery and the power consumption of your device. Generally, you can expect most laptops to run another two to three hours off an external battery that stores around 60W, and a battery with a capacity of around 120W should power your notebook computer for another five to six hours. External batteries typically connect to the DC input jack of your portable device (the same hookup you use for the AC power adapter) through an included cord that may feature adaptable connectors. We should note that DC input jacks vary in size, and you'll want to make certain the external power source includes connector tips that fit your portable device's DC input jack. Contact the external battery's manufacturer or visit its Web site to ensure a connector tip is provided for your device.
A program utility that moves a program from storage into memory, where it can begin operation.
(Pronounced bye-ose) A special piece of software built into most computers. BIOS routines control the startup process of the machines and other basic functions such as the keyboard, display, and disk drives. On older computers, the BIOS is stored in read-only memory, which is not erased when the power to the computer is shut off. Newer computers store BIOS on flash ROM, which can be erased and rewritten if the user needs to update the BIOS program.
To delete or remove data or a file.
To swing back and forth, such as the waving arm of a metronome. The electrical meaning is a complete cycle of alteration.
The act of touching a metal surface to discharge static electricity. It's always wise to ground oneself before working inside a PC because the static electricity can damage electronic circuits inside the PC's case.
A measure of printer resolution that indicates how many ink dots the printer can place in one square inch. The larger the pi, the sharper the printed image. A text printer should have at least 600dpi; a graphics printer should have at least 1200 x 600 or 1200 x 1200 dpi.
A data-file copy stored somewhere other than the location of the file from which the copy was made. An archive copy helps ensure against permanent data loss, which may occur in cases of system failure or natural catastrophe. Backing up files to a diskette or a tape drive is one method of archiving data. Extremely valuable archives often are stored in fireproof vaults, underground bunkers, or at sites hundreds of miles from the original data source.
A measure of the brightness consistency on a computer screen. A screen with areas of darkness has poor uniformity. You can easily spot a monitor with poor uniformity when looking at a plain white background on its screen.
If you can access the Internet when you connect directly to your broadband modem, but not when you put a router between the modem and your PC, one solution is to reset your network devices. This gives them the chance to reassign IP (Internet Protocol) addresses and connect to each other without conflicts. To completely reset your network devices, power off your PC and then unplug your broadband modem and router. Leave the units unplugged for a few minutes. Consult your device manuals to determine whether you need to perform any additional tasks to reset the devices (some units have Reset buttons, for example). Finally, plug in and power on your devices, starting with the broadband modem, then your router, and then your PC.
Pronounced “wares,” a term for copyrighted software made available illegally for downloading from the Internet. Also, any method used by software pirates to acquire applications without paying for them.
An html (Hypertext Markup Language) code used to index pages. The tag includes such things as keywords and page descriptions for a Web site.
Describes any new user of computer or Internet technology.
The exploration of a network to determine topologies, IP (Internet Protocol) addresses, database information, etc.
Copyrighted software distributed on a free-will donation basis either via the Internet or by being passed along by satisfied customers.
Most PDAs have a Reset button. If your PDA freezes, or if your software installation requires it, you may need to perform a soft reset by pressing the Reset button.
Slang for traditional paper mail sent by a postal service, taken from its relative slowness to arrive compared to electronic mail.
An instrument that increases a signal's strength so it can be transmitted and received over a greater distance without a loss in quality.
Advanced technology used for page layout formatting of text. Rich text can include fonts, borders, underlining, italicizing, and other formatting. Rich text requires more storage space than plain text.
Email that a person can access from any computer that has Internet access and a Web browser. Examples of these accounts are Hotmail or Yahoo mail.
Refers to a digital image that is too dark or wasn't exposed to enough light.
The system unit space reserved for the installation of any type of drive. These slots are usually located on the front panel of a computer. Empty drive bays may be protected by a plastic cover. To install many types of add-on components, an empty drive bay is required.
Different cell phones support different types of ringtones. A polyphonic ringtone uses your phone's ability to emulate instrument sounds and play multiple tones at once. Phones that are polyphonic-capable can play up to 40 notes at once, but are unable to play lyrics. In comparison to monophonic ringtones that can only play a tone-based version of a song, polyphonic ringtones sound more like the original song. Conversely, because polyphonic ringtones can't include lyrics, they're apt to sound less like the original song than a full music ringtone that includes lyrics and sounds nearly identical to the full version of an original song.
Multiple cores (the central brain of the chip) contained on one chip. Having dual or multiple cores allows a chip to divide computing tasks efficiently, which allows more computing work to be finished in a shorter amount of time than a single-core chip would have used to do the same work.
The set of available colors in a given computer graphics program or computer system. Palette also can refer to the collection of tools in paint programs used for creating and altering images.
To transmit a message or article for publication on an Internet newsgroup or bulletin board.
The ease with which software can be moved from one computer or operating system to another. Portability can be defined as either high or low. High portability implies the software is easily moved to other systems; low portability means it can be moved with great effort, similar to the effort put into writing the original program.
A technique used by some search engines, with the most popular Web site listed first. The number of sites that link to the ranked site determines popularity.
A group of hardware components used to secure monitors, network hubs, and other hardware items to walls or desks.
Correcting the brightness, contrast, or color of computer graphics on a printer, monitor, or scanner so graphics are uniform on a monitor or hard copy.
This top-level domain name is reserved for Web sites affiliated with the U.S. government. It is used in URLs (uniform resource locators) to identify a site as a government Web site. For example, www.whitehouse.gov or www.firstgov.gov.
The number of bytes, or characters, a disk can hold; the maximum storage volume of a disk. Capacities are usually stated in kilobytes (KB or K), megabytes (MB), or gigabytes (GB).
In terms of data encryption or decryption, key length is a measurement of how secure the encryption key is. In general, the longer the key length, the more secure the encryption is.
>computer science To start running a computer program from the very beginning, without being able to continue the processing that was occurring previously when the system was interrupted.
In computers, to bootstrap or "to boot is to load a program into a computer using a much smaller initial program to load in the desired program which is usually an operating system.
A core dump is the recorded state of the working memory of a computer program at a specific time, generally when the program has terminated abnormally, crashed.
Input is the term denoting either an entrance or changes which are inserted into a system and which activate/modify a process. It is an abstract concept, used in the modeling, system (s) design and system(s) exploitation. It is usually connected with other terms, e.g., input field, input variable, input parameter, input value, input signal, input device and input file.
Input/output, or I/O, refers to the communication between an information processing system such as a computer, and the outside world – possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation. I/O devices are used by a person or other system to communicate with a computer. For instance, keyboards and mice are considered input devices of a computer, while monitors and printers are considered output devices of a computer. Devices for communication between computers, such as modems and network cards, typically serve for both input and output. Note that the designation of a device as either input or output depends on the perspective. Mice and keyboards take as input physical movement that the human user outputs and convert it into signals that a computer can understand. The output from these devices is input for the computer. Similarly, printers and monitors take as input signals that a computer outputs. They then convert these signals into representations that human users can see or read. For a human user the process of reading or seeing these representations is receiving input.
Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware thus making it behave as expected. Debugging tends to be harder when various subsystems are tightly coupled, as changes in one may cause bugs to emerge in another.
If Windows displays an error message that a keyboard isn't present or characters you type aren't displaying on-screen, check the connection to the computer. Shut your system down and then look at its back to make sure the connector is securely plugged into the proper PS/2 or USB port. PS/2 keyboard ports are typically colored purple, and the connector will only fit one way. Check also that the connector's pins aren't bent or broken. It's possible to gently bend a pin back in place, but if it's broken, replacing the keyboard is your only option./p>
If the pins are fine but you suspect the board isn't receiving power, plug another keyboard into the computer. If it works, your keyboard's circuitry may be damaged, and you'll likely need a replacement. If the substitute also fails, the PS/2 or USB port or a motherboard controller may be bad, and it's possible you'll have to replace the motherboard. Finally, if the keyboard is plugged into a USB hub, the hub may not be capable of supplying sufficient power to the keyboard. Try connecting the keyboard directly to a dedicated USB port.
Memory-related error messages that appear when your computer first begins booting usually point to a bad memory module. The computer performs basic tests on all hardware when it's first switched on. If the information it writes to memory is not the same as the information it reads from memory, the computer stops booting and displays an error message.
In most cases you'll need to replace the bad module. If you have recently installed new memory, however, the problem could be a compatibility issue. Try removing the new memory and see if it solves the problem.
If you have multiple memory modules, try booting your PC with just one module installed at a time. This will help you isolate the bad memory module.
Also known as smileys and short for emotion icons, these punctuation combinations form small pictures, often best viewed sideways. Emoticons are most often seen in electronic mail (email) and Internet messages.
Operations such as printing that are being held, usually in the order received, before the computer executes them. Also refers to lining up these operations. When referring to programming, it means to remove data elements in the order they were entered.
Software that allows two otherwise incompatible programs to communicate with each other. The middleware converts data from one program to the other, and vice versa. Middleware is most often used to connect databases.
A term used to describe the gap that exists between people who have the capability, access, and knowledge to use modern technology and those who do not.
An authorized access level that each network user is assigned, either as a user, an administrator, or as a guest. This determines what information he or she can and cannot have access to.
Speakers used in a surround-sound configuration. The satellite speakers are used as the front speakers, usually placed to the left and right of the sound system, facing out.
A type of software designed to let users on a network use the same software and work on the same projects at the same time. A popular groupware product is Lotus Notes, which is software that, among other applications, lets users work on the same documents and exchange email.
The person who uses hardware or software programmed or designed by another person.
To put two sets of data together while keeping the integrity of each intact.
Off-the-shelf software available in stores, as opposed to custom software created for a specific company or individual.
A removable container that holds toner for a laser printer and which can be thrown away when empty. Some toner cartridges contain only the toner, while others include the photosensitive drum, making it less likely that someone will touch the drum and damage or mark up its surface.
Back-hack refers to the art of tracking a hacker who has broken into your system.
The result of a successful ping, or test of a network connection’s performance. If the site or device you ping is operating properly it sends a return transmission called a pong.
How much activity is taking place on a communications system. Too many users on a network will lead to more traffic than the system was designed to carry, or a kind of traffic jam. Overloaded networks will sometimes malfunction, so network administrators work to control traffic.
A measurement used to describe the height of a printed character. A single point is 1/72 of an inch.
A place on a text line where the cursor goes when the TAB key is pressed. In word processing documents, tab stops usually are placed at regular intervals across the line but can be set wherever the user wants them.
The ability of a machine to recognize patterns and improve future performance based on this experience.
The way an application fundamentally arranges and presents data. One example of a native file format is the way Microsoft Word inherently arranges and presents text in a file with a .DOC extension. The native file format may be associated with one program, or it may be universally accepted.
Refers to the actual act of creating a key, which is a string of bits used to encrypt or decrypt data or information for security purposes.
The integrated circuit, known as the CPU (central processing unit), that controls the computer. Microprocessors cram more than 1 million transistors into 1 square inch of space. Microprocessors are responsible for interpreting instructions gathered from input devices and transmitting the results to output devices. Though there are many types of microprocessors, the two main families used in PCs are made by Intel and AMD.
An abbreviation for robot. Bot usually refers to software that executes some function automatically. Search engines typically use bots to seek out Web sites and record information about the sites for future search purposes.
Information that comes out of a computer after processing. Output can be displayed on a screen, sent to another computer, or stored on a variety of storage media.
A device that boosts the strength of a signal before sending it down a line. A line driver increases the transmission distance, which helps to ensure the signal reaches its destination.
To stabilize a PC after an error has occurred. If used in conjunction with a program, to recover means the program stabilizes itself and returns to use without user intervention. Often "recover" is used to describe getting files back after a hard drive error. In this case, a recovery program searches for whatever information remains in storage. Whatever is found is "recovered."
A highly sensitive device that converts light into an electrical signal. Solar-powered devices use photosensors.
A computer designed for use by a single user, with everything a user could need for basic computing, including the ability to process and store information. IBM introduced its first single-user computer as the IBM PC in 1981, and in the last 15 years, the term has come to represent any computer based on the IBM standard. The other standard in the personal computer market is the Apple Macintosh. Software and peripherals specify whether they work on IBM-compatible PCs or Apple Macintosh platforms. In addition to standard abilities such as word processing, PCs have brought a wide variety of new possibilities to home users. Today a PC can be used to play high-tech video games, access huge amounts of information, and contact people around the world. The growth of the Internet and the World Wide Web has opened up a vast new world of opportunities for PC users.
The ability of some word processing applications to automatically insert a list of addresses and other information into form letters. The user sets up a document laced with special codes indicating where addresses and names will be inserted. This document is then combined with a list of names and addresses. The results can be printed or stored as separate files. Mail merge saves the user the hassle of repeatedly typing the same text. Also called print merge.
Any device connected to the computer that performs a specific function. Printers, keyboards, diskette and tape drives, and monitors are among the most common types of peripheral devices.
A term used in jest by users to describe the fictional place where information or data lost in transmission on the Internet winds up.
A computer that exists on the same level as another with similar access privileges on a network.
The plural term for computer storage material such as diskettes, hard disks, and tapes.
A word, term, or expression recently invented or given a new meaning. One example is wallpaper, which, before computers became widespread, meant the material you cover a room’s walls with. The rate of neologisms has increased with the introduction of new technology, most notably, the Internet, which has spawned such terms as intranet, extranet, emoticon, and netiquette.
A camera lens that can be attached to some cameras to produce a very specific effect. A fisheye lens is a very wide angle lens that takes straight lines of an image and displays them as curves. Typically, a fisheye lens focuses more intensely on the center of an image, while at the same time focusing less on the outer edges of the image.
A method of keeping email messages safe from encryptions while they transmit. Chaffing adds false packages to a message when it is sent and removes those packages when it is received, making it impossible for anyone but the intended recipient to understand the message.
To improve a scanned photo image using the tools available in a photo manipulation program. Improvements can include everything from more refined colors to improved clarity.
A measurement or degree of an image's on-screen clarity. The smaller the dots that make up an image and the more dots used, the clearer the image. Bigger dots make the image appear grainy. Granularity also refers to the degree of difficulty in searching a database and manipulating data. If a search's features are not specific enough, a database might be considered quite granular.
A type of texture mapping that accounts for depth while rendering images. By doing this, objects that are supposed to be closer are larger, and those that are farther away appear smaller.
The pattern of a signal, such as that generated by sound and light, that changes at regular intervals.
A communication or program error that results when a response is not given in a specified length of time. For example, you can be disconnected (sometimes called "kicked off") from an online service if you do nothing for a certain period of time. Some programs let you choose the length of time after which the program times out, so if you walk away and accidentally leave the program open, it won't keep running indefinitely.
An item, either hardware or software, that is available for a computer to access during an operation. A resource can be accessed by a single computer or through a network and includes items such as a system's hard drive or a shared printer.
A function built into a system's hardware, rather than software, to perform a task. The capability to perform a task can be built in through an extra microchip, instead of programming the task into software. For example, some computers might include MPEG (Motion Picture Experts Group) video as hardware instead of relying on software to do the job. However, the term occasionally is used when referring to software. It might also be said that a feature is hardwired into software if that feature cannot be manipulated or changed by the user.
To place in between. In computing, it means to place something between data, information, or any other pieces of a document. For example, you can insert words anywhere in a word processing document.
A "signature," such as a nonfunctioning symbol or picture, that microchip designers often add to their chips to add a personal touch to their handiwork.
Transmitting data from point A to point B, whether the points are on a communications link or between components on a computer system.
This database feature locks an object before the object is updated. That way, the user will be sure no one else accesses the object during the update and ensures that the update will be made.
A blank section of videotape. Video black is often used to separate different portions of a program on the tape and at the very beginning and end of a tape.
Pixels that are improperly displayed after the mouse pointer moves across a PC screen. This happens frequently if a mouse driver doesn’t work with the current graphics mode.
A key or combination of keys, such as CTRL and an alphanumeric character, that activate a pop-up program or cause some other predetermined action to occur. For instance, SHIFT and F7 are hotkeys used to print in DOS versions of WordPerfect.
The range of frequencies from 3KHz to 300GHz on the electromagnetic spectrum between light and sound. These frequencies are used by devices such as AM and FM radios and baby monitors, or for communications between satellites.
The ALT (Alternate) key on a computer is used in conjunction with other keys to give a key an additional function other than the one indicated by its label. The ALT key is similar to the CTRL (Control) key. For instance, employing the ALT-F key combination in most Windows applications will open the File menu. When using the ALT key, it is best to press the ALT key and, before releasing it, press the other key desired.
These kinds of viruses try to avoid detection by antivirus programs by changing their code. The structure or code of the virus will appear to be different on different systems, which may confuse the antivirus software.
An action that happens when you begin clicking the mouse before the software is prepared to accept new input. This happens most often with programs you’re so familiar with that you know when and where you need to click before the program is done loading.
A computer that shares information with other computers, or the act of sharing information with or providing services for other computers. Examples of host computers include a file server, which shares files and programs with other computers on the network; a Web server, which shares content with the rest of the Internet; and a mail server, which accepts email messages and sends them to the intended recipients.
A hypothetical disease describing the breakdown or decay over time of the underlining binary instructions that make up a program or a data file. Bit rot can be brought about by physical processes. Computers contain error correction codes to compensate for bit rot, but large amounts of bit rot may result in a program that’s so rotted it will no longer run.
A video device that captures images from video and then changes them into a digital form the computer can understand. A grabber can refer to the hardware card that captures the video frame or the software that grabs the image and stores it as a file.
Hardware devices, such as servers or monitors, designed to be installed on a metal frame. Also describes devices already installed on a metal frame.
In software development, a group of people who volunteer or are paid to test new applications with the goal of determining the code’s security weaknesses.
An annoying impasse where two pieces of equipment, such as modems, PCs, networks, and fax machines, that are attempting to communicate with each other are both sitting idle, waiting for the other to begin the transmission. While the name is amusing, and bears some nostalgia for those awkward junior high days, the equipment deadlock is anything but funny, especially when you're waiting for a data transfer.
The momentary lingering of previous images on a changing computer display.
From kilo binary byte, a unit of measurement that is equal to precisely 1024 bytes. Similar to the more common kilobyte. Kibibyte came about because the prefix “kilo” may refer to 1000 units or 1024 units, whereas Kibibyte strictly refers to 1024 units.
Short for micrometer, the unit of measurement used to measure the core of a fiber-optic cable, or more commonly, the elements that create the transistors on a CPU (central processing unit). A micron is one-millionth of a meter, 1/25,000 of an inch, or 1/50 of the width of a human hair. The first 486 processor measured 1 micron and the first Pentium measured 0.8 microns. The smaller the chip, the cooler and faster it can run.
The smallest part of an image that a computer printer or display can control. An image on a computer monitor consists of hundreds of thousands of pixels, arranged in such a manner that they appear to each be connected. Each pixel on a color monitor comprises three colored (blue, red, and green) dots. The term comes from the words picture element, and also is abbreviated PEL (pronounced pell).
Any indication that a text block or an object has been selected with a mouse-click or the arrow keys on the keyboard. The highlight may appear as a change in the color of text or as a border around an object. A highlighted object is usually ready for some type of operation, such as deletion.
A book or a computer program that contains a set of instructions about how to use a piece of software or hardware. Most computer products are sold with some sort of users manual included in the package; manuals written by third parties can be obtained from retailers of books and computer products. In many cases, the third-party manual can contain more tutorial and troubleshooting information than the manual that was provided by the manufacturer.
Distinct pieces of information, which can exist in various forms such as numbers, text, bit, bytes, or memory. This information can be processed and translated by a computer, and as a result, text, pictures, or sound appear on-screen.
One or more keys that, when pressed together, equal a menu function or other function in an application usually reached through a mouse-click. Keyboard shortcuts usually are not as intuitive as point-and-click mouse commands, but the frequent user of a program can save time by learning them. One shortcut in many programs is CTRL-X, which equals the Cut option found in many Edit menus.
An organized directory of pages on a Web site.
A technology that lets a user view a smaller window within a larger display. For example, with a PIP display, a person can channel surf in a corner of a television screen while watching another channel. In addition to television, PIP is often used in video conferencing.
A process that allows one person at a time full access to files contained in a network database. Locking prevents two people from trying to make changes on the same file at the same time. In most situations, a second user may view the file, but only the first one can make content changes.
A personalized list of contacts with whom to communicate online. Coined by AOL, a buddy list informs the user when a contact is logged into the network so the two acquaintances can converse online.
A printer far from the user. It could be a shared printer in a secluded area of a building or, with the advent of printing over a network or the Internet using IPP (Internet Printing Protocol), a printer thousands of miles away.
A term used in programming to denote a reusable section of code. Object-oriented programming methods use objects as the basic building blocks of programs. Objects are generally standardized so they can be used in many different types of programs without having to be rewritten each time. In graphics, the term is used to describe a distinct element, such as a block.
Information from a Web site sent to a browser and stored on a user's hard drive so the Web site can retrieve it later. A Web server using the technology looks for a cookie when a user visits. Cookies generally are used to identify visitors. A cookie can contain information about the user's login name, password, and preferences. For subscription sites, the cookie can make it unnecessary to log in each time. Users have the option to configure their browsers to either accept or reject cookies.
redundant array of independent disks
Any component, bus, or interface that slows down an otherwise faster system or network. For example, an external hard drive and its host computer will likely be constrained by a slow parallel port connection between them. Likewise, a 56Kbps (kilobits per second) dial-up modem connection can be considered a bottleneck between a fast Web or cache server and your PC.
Storage space that houses huge, outdated mainframe computers.
A term used when a system only contains one hard drive inside the computer's case.
A term used to describe someone who seems to have become only accessible through electronic means, such as email or video talk, and is no longer accessible by phone or in person.
Parts located in a printer that stretch across the width of a page and pull the paper through during the printing process.
Any computing device worn on the body. Some wearable computers are portable multifunctional devices such as a PDA (portable digital assistant), mobile phone, and MP3 player designed to be worn for easy access. Some wearable computers even include a head-mounted LCD (liquid-crystal display) screen. Prototypes for future wearable computers include specially-designed power-generating clothing such as a shirt with solar cells.
Refers to an Internet site that hosts text-chatting functionality. The term is most popular among users from the United Kingdom.
Areas of light around bright objects that appear on a computer monitor when they shouldn't. The halo effect is a sign of an inferior monitor.
A particularly small footprint. Manufacturers use the term footprint to indicate how much desktop space a product consumes.
To switch between settings, such as on and off. Also can mean the actual switch that controls these settings. For example, in Microsoft Word, the buttons controlling the switches for bold, italic, and underlined text are toggle switches, because each of those text characteristics is either on or off when the buttons are clicked.
Used to represent 1 billion, or 10 to the ninth power. In computer terminology, however, the prefix giga means 2 to the 20th power, or 1,073,741,824.
A measure of how easy it is to upgrade a particular hardware or software product. For example, on a small network hub, how easy is it to add more ports to the network? Or, if a company bought a powerful computer for a Web server, can they significantly upgrade the hard drive and RAM (random-access memory)? Software scalability indicates that a product can handle heavier usage if it's given more computing power or memory. Programs that aren't scalable will crash under heavier usage conditions even if there is plenty of memory or computing power available. Scalability is a very important feature for hardware and software to have. If you're making a significant investment in a product, you should be confident that you can add to it and use it for years to come.
A separation process that divides and arranges digital information.
An email that is returned undelivered before being accepted by the recipient's server. A common cause is a misspelling of the domain name or the second part of the e-mail address. For example,if the sender enters email@example.com instead of firstname.lastname@example.org, a hard bounce will occur.
A file at the bottom of a hierarchical file system that can have nothing below it. Using a tree structure analogy, the leaves connect to the branches, which connect to the roots.
A specific location in a computer's memory where keystrokes from the keyboard are stored until the computer acts upon them. This allows fast typists to continue typing even if the computer is unable to immediately display the letters.
Slang term for Internet congestion. Large amounts of data are clogging a network, slowing down network performance, not unlike traffic during rush hour.
Memory buffers your computer uses like sticky notes to decide which piece of hardware is next in line to work.
Similar to pen pals, key pals are two users who communicate frequently by email instead of written correspondence.
The processing of information. The retrieval, sorting, modifying, filtering, and querying of data are a few of the primary methods of data manipulation. Essentially, data already must be present within a file or database for data manipulation to occur; it does not involve entering new data. The creation or deletion of files, however, is considered part of data manipulation.
A generic term used to refer to electronic paper. E-paper exhibits some of the same properties as paper. It’s thin, flexible, and inexpensive. Using special devices, however, you can create an electric image on the paper. Unlike paper, e-paper is completely reusable.
A circuit board in a computer that controls display factors such as resolution, colors displayed, and speed of images displayed. A video card cannot bring an older monitor up to its standard. Both the monitor and the video card must support a resolution, such as 800 x 600, for that resolution to be possible on the system. Today's video cards typically contain some memory so that the PC's RAM (random-access memory) isn't bogged down with handling displays. Some cards, often called video accelerators or graphics accelerators, contain a graphics coprocessor that handles graphical computations. Also called a video adapter, video board, or video controller.
A pause in a microprocessor's clock cycles that allows for differences in speed between one component and others in a computer (such as input/output devices or RAM). Wait states are common in systems where the microprocessor has a much higher clock speed than other components, requiring the latter to "play catch up." During a wait state, the microprocessor idles for one or more cycles while data comes in from RAM or other components. Although unnoticeable to users, this idling can affect a system's performance because it involves the microprocessor's clock speed; if clock speed is reduced, system performance will slow. Wait states also are not uncommon between buses and expansion cards, where the expansion cards run slower than their buses.
The insulation that surrounds the core of a fiber optic cable. The cable jacket is placed on top of the cladding.
A conflict when more than one computer, or more than one program in a single computer, tries to access the same resource at the same time. Different systems and networks respond in different ways; some require all parties to access the information again, while others operate on a first-come, first-served basis.
A capability of a modem protocol that lets two modems lower their speeds to compensate for transmission problems.
Action or characteristic related to the entity as a whole. For example, an action that affects an entire file, directory, program, or project.
In multitasking environments such as Microsoft Windows, several applications can run simultaneously. One runs in the foreground while the others run in the background. The application or window in the foreground is active and can accept user input with a mouse, keyboard, or other device. Applications in the background cannot accept user input, but they still can run internal processes such as printing, reading and writing data to the hard drive, or performing calculations. In Windows, users can move background applications to the foreground by pressing the ALT-TAB key combination or by clicking a background window. Background also can refer to the color of the screen in DOS or Windows environments. Background colors can be selected according to the user's preference.
A technique that stifles the response of a circuit or device so it does not exceed certain limits. Damping is used to pace the flow of electricity or information within the computer.
The part of a network that carries the majority of the data traffic. Backbones connect smaller networks, or nodes, together to create larger networks. Backbones usually transmit data at higher speeds than the rest of the network. On large networks, such as the Internet, there may be more than one backbone, all of which span long distances. On smaller networks, the backbone sometimes is called the bus.
Gesture recognition refers to the ability of a computer to read and accept human gestures as input. Instead of moving a mouse or keyboard, for instance, a simple pointing gesture might do the trick. Gesture recognition has a number of applications ranging from helping disabled individuals to video games. Gesture recognition usually involves the use of some sort of camera connected to a PC.
An object used to absorb and eliminate heat to prevent overheating and breaking down. Some computer components generate heat as they operate because they run so quickly. Computer manufacturers often install these small metal devices on powerful microprocessors.
A help system featured in many applications that uses small pop-up "balloons" of text that appear when the cursor is moved over certain spots in an application's interface. The balloons usually describe the function of a button on a toolbar. Similar to tool tips, which are rectangular pop-up help words that appear in many Windows-compatible programs.
In a network system, a data frame is a packet of information transmitted as a single unit. This data frame exists only as it moves along, encapsulated, on the connecting cables or line. The information takes another form before and after the transmission.
Any type of storage medium, such as tapes and diskettes, in which magnetic patterns represent stored values.
To test aspects of computer hardware or software against a known standard. When used as a noun, a benchmark usually is the result of such a test. Benchmarks are only useful if all computers or applications being tested are tested under the same conditions. When measuring the speed of computers, for instance, a benchmark utility program should attempt to perform the same operations with each machine. It also is necessary to know exactly what a benchmark is designed to test. A machine that is speedy at one type of mathematical operation could be slow at other tasks.
The slot or opening at the top of a diskette that provides access to the magnetic diskette inside. The read/write head in a disk drive must directly access the magnetic diskette to store and retrieve information. To get to the magnetic diskette through the head slot on a 3.5-inch diskette, the drive moves a metal cover off to the side. It's simpler for a disk drive to get to the magnetic diskette inside a 5.25-inch diskette because the head slot is always uncovered.
When an object or icon dragged across the screen leaves a trace behind it.
To synchronize the movement of an on-screen pointer or cursor with that of an input device such as a mouse. Also, the spacing between letters and words.
A term used in multiplayer console, PC, and Internet gaming that refers to a player who directs his or her game character to stay in roughly the same spot for the duration of the game. Sometimes campers stake out a spawn point (a location where others players returning or entering the game appear) to get an unfair kill. Other times a camper stands near a valuable item spawn point to horde that item. Campers are generally not considered to be breaking the rules, but the activities they engage in are frowned upon by most gamers.
The destination file or device where source data is moved, copied, or stored, whether transferred internally or over communication lines. For example, if a user wishes to download a file from the A: drive into the C: drive, the A: drive is the source, and the C: drive is the destination and therefore the target. The target can also be the audience for whom a certain product is designed.
Each individual request made in a Web server's log. The number of hits a Web page receives equals the number of times a part of that page has been accessed. One Web page could receive as many hits as it has files to download. Typically a page will include an html (Hypertext Markup Language) text file and several other files including graphics, sound, video, and/or text. Thus a page made up of one html file and nine graphics files that receives 1,000 hits has been viewed 100 times. This information can be useful, but many advertisers are more interested in page impressions, which count the actual number of visits to a page.
To input information into a computer using a keyboard or numeric pad. Often used to describe the inputting of large amounts of data into a database.
Perpendicular lines on the edge of an on-screen image. Jaggies are caused by a monitor resolution setting lower than the one the application requires or by a font or graphic with poor scalability. Also called jags.
An executable program capable of performing a specialized function other than system maintenance (which is performed by utilities). Games, educational programs, and communications software are all examples as are word processors, spreadsheets, and databases. Also called software.
These devices, also known as Web cams (or Webcams) and desktop digital video cameras, are small, focus on one object (such as a person sitting at a computer), and usually sit on top of a PC monitor. Web cams capture still images and video motion, and then transmit this data for such purposes as video conferencing, video email, and enhancing Web pages.
In computing, the process of using software to manipulate images and sounds within a video media file. This can involve adding sound effects or music, shortening or rearranging segments, or adding transitions or other visual effects.
Any method of condensing information so it can be stored in less space or transmitted in less time. Many large graphics and sound files are compressed so they can be downloaded faster. Although data compression can be done in many ways, a compression program generally looks for redundancies in a file, then compresses the identical pieces of data into one representative token. Also called data compaction.
A length of cable running between different PC components or between devices on a network. A segment can consist of a single cable or multiple cables connected to each other.
The identifying title given to a system of computers, usually including the top domain and all of its subdomains. For example, a domain name, such as socrates.nd.edu, indicates that the Socrates network is found at the University of Notre Dame (nd), which is an educational institution (edu).
Stored data that can be accessed but not altered. Usually, this term refers to information that can't be physically altered. For example, traditional CD-ROMs are created by a method of creating pits in the storage medium. Users usually can read, but not change, the information stored in this way. Read-only also may refer to the status of a file. For example, files can be placed in read-only status for security purposes. This status is used for documents such as newsletters that are available to all users on a corporate network.
The area in the computer where cards are installed. The area usually has protective metal and mounting brackets. The term comes from an external, cage-like box where cards were on older computers.
In the computing world, there are typically two kinds of skins, one refers to images or themes that change the appearance of a user interface, and the other refers to the ability to change the look of a character in a video game. You can change the look for Web browsers such as Microsoft Internet Explorer and MP3 players such as WinAmp by adding a skin to it. Skins are usually based on a specific theme such as a movie or type of product. Video game skins are options that players can use to enhance the look of characters in a game by giving the character different clothes, for example, or by changing the character's gender or species. In both cases, end users can create their own skins and incorporate them into the programs.
In communications, a registered or billed connection with a network, an online service, or an ISP (Internet service provider). Online accounts are used to keep track of connect time and monthly service costs. In multiuser networks and operating systems, accounts primarily are used for identification purposes.
A small (usually about one inch square) sticker or metal plate applied to a computer case depicting the logo or image associated with the computer's manufacturer.
A device that locks hardware or software to prevent unauthorized use. Often a small metal key that secures the hardware contained within a computer case. The dongle can prevent a computer from being booted.
A file designed to store information while a user is working with that file. Temporary files are retrieved from storage by an application and manipulated by the user, leaving the original file intact until the user saves it under the original file name. Temp files are created automatically by applications and usually are deleted automatically when they are no longer needed. The user can delete them, however, to recover disk space. Also called a temp file.
Any device or circuit that allows electrical currents to travel in one direction only.
A term used to describe a monitor screen distortion that displays defocused images and reduced detail and sharpness in bright objects. Also refers to a problem with some digital camera sensors. Blooming occurs when camera sensors become overcharged, resulting in blurred details.
A row of boxes, often at the top of an application window, which control various functions of the software. The boxes often contain images that correspond with the function they control. In Microsoft Word, for example, the box that controls the print function contains an icon of a printer inside it. In most programs, toolbars can be turned on and off and often can be personalized with controls specific to an individual user's needs.
Technology that lets a computer “speak” in a human-sounding voice. A current application for voice synthesis is called text-to-speech. UC (unified communications) applications let a user retrieve her email messages over the phone, among other things. Using text-to-speech, the message server will “read” the user’s email to her.
Often blogs will have links that lead to other blogs. Blog hopping involves following links from one blog to another while also visiting related sites, forums, and articles.
Data inserted into copyrighted work that contains vital information, such as the author and copyright dates. Such watermarks can be viewed only with the correct software and are designed to be invisible to ordinary users.
To intentionally and prematurely terminate an active computer command.
The popular design for portable computers, with a shallow case hinged at the back so the screen folds up from the keyboard.
A specified operation completed by the system. A job can be as simple as saving a document or as complex as organizing data into a report.
To end prematurely, hang without allowing user input, or otherwise fail. Applications are said to bomb, while entire systems usually are said to crash. However, the terms can be used interchangeably. In Windows, the CTRL-ALT-DELETE key combination sometimes can regain control of or end an application that has bombed.
An intermediate Web page that can prelude a Web site’s home page. When users click an advertisement, the ad tag sends them to a special site the advertiser has created to continue the ad. Jump pages often include rich media. Also called a splash page.
The collection of icons, graphics, and text displayed on-screen at a given time.
A biometric technology that measures the characteristics of a user’s voice against templates created during initial use. Users speak into a microphone, and the computer measures variables such as cadence, pitch, tone, and the shape of the speaker’s larynx to verify identities. Since users can easily change some of the variables involved at will, voice verification is not considered as accurate as other biometric techniques such as retinal scans or fingerprint verification. However, it is generally cheaper to implement than such methods because it doesn’t require special or costly hardware.
The process of converting linear pictorial images into digital data for storage. For example, a scanner converts a non-digital image, such as a portrait or photograph, into a digital format of positively (1) and negatively (0) charged signals so the image can be stored on a hard drive. Likewise, a sound card can digitize a sound by translating it from analog (its actual sound) to digital (a form that can be read by a computer).
A packet of legal paperwork that allows users to purchase the use of a software company's product. It does not transfer ownership. Most license agreements appear on a software's package, and when the package is opened, users agree to the terms listed.
The digital version of an image, photograph, or picture displayed on a monitor screen. The computer must change photographs or other images into the digital form of files for it to understand and work with them.
An electronic form used to gather information about a user. E-forms are used to provide feedback, make inquiries, order merchandise, sign up for services, and more.
The darkest black a computer monitor is capable of producing. The black level in a good monitor should be purely black.
A kind of printer feed used with continuous-feed paper that has holes along the left and right sides. The tractor feed is named for the sprocketed wheels, which look like tractor wheels, that fit into the holes in the paper and pull the paper through the printer. Also called tractor feed.
To execute a program one step at a time. Usually used to find the flaw or error that is causing a program to run improperly.
In a leapfrog attack, a malicious user "borrows" a user ID and password from any of a number of sources, such as a file containing IDs and passwords, and uses it to penetrate another system. A user can also use this tactic to make it difficult for other computers to trace him.
This number represents the number of times a software program has been downloaded from the Internet by users. It is often used to signify a program's popularity.
A pen-shaped instrument used with graphics tablet or touch screen input devices to write or draw on the computer screen as on a sheet of paper.
A computer that has two OSes (operating systems) installed, each in a separate partition. When the user starts the computer, a menu appears from which the user can choose the desired OS.
Refers to the way a gamer interacts with other elements in the game. Often found in game reviews, the term is also used as a means to rate the quality of the experience the player had while playing a particular game.
Refers to changing the resolution of a digital image. An image can be resampled up or down, meaning the resolution can be increased or decreased with the use of software.
A mickey is the unit of measurement used in determining the speed and movement direction of a computer mouse. The speed of the mouse is determined by the ratio of how many pixels the cursor moves on the screen to how many centimeters the mouse moves on the mouse pad. Directional movement is referred to in terms of a horizontal mickey count and a vertical mickey count. One mickey is roughly 1/200 of an inch.
A method of storage used by a router that keeps track of addresses and host names to provide quick access when future packets are sent.
A software-activated division of the screen in which different documents can be displayed. Each document can be manipulated individually. Also called split window.
The fear of being ignored or ostracized in the online community brought about by delays in Internet chat rooms, message boards, and Internet telephony communications due to a network lag. People communicating by such means may experience laganoia if responses to their messages are a long time coming. Sometimes, though, other users are responding, but responses take a long time because of poor bandwidth or problems with transmittal from one portion of the Internet to another.
A component of a network, typically a NIC (network interface card), that is operating incorrectly. A jabber will send a continuous stream of incorrect or meaningless data to the rest of the network, which could cause the entire network to stop working.
A section of a message, ordinarily at the beginning, that routes it to its destination and often identifies the sender. Another type of header is text such as numbers or chapter titles that appear at the top of each page in a document. In data storage, a header lists a file's name, size, and the time and date of its creation or revision. In a database, a header is a record identifying the fields and kinds of information in the following data records.
The unpredictable area of a network that data passes through. Clouds exist because data sent in packets can take various paths to reach the same end point.
A device conflict occurs when a device attempts to access a port that is in use by another device.
Early batteries often used some sort of liquid solution as an electrolyte. This liquid solution could spill or leak and was often harmful if not Handled properly. Dry cell batteries eventually replaced wet cell batteries because they were versatile and durable.
Slang for each of the smaller companies a breakup of Microsoft would create. When the Department of Justice declared Microsoft a monopoly, it proposed That Microsoft split into two companies, or Baby Bills, an applications-based company and an operating systems-based company.
A printing technique that produces a replica of each character in a lighter shade and slightly off center so it appears the letter has a shadow.
A term used to describe an increase or decrease in electrical power that can damage the circuitry of a computer. Dirty power can be in the form of spikes or surges.
A computer and a display screen that display information in public areas. Kiosks can display simple rotating graphics or html (Hypertext Markup Language)pages. More complicated, interactive kiosks allow a user to access the information they want. Kiosks are used to provide information about a specific location,to provide directions, or to provide countless other services to the public. An ATM is a good example of a kiosk.
The form in which information is transmitted within a computer or a network. Data signals usually are binary codes transmitted between devices. Data signals might consist of viewable information, such as documents or graphics, or internal computer information, such as virus checks or control characters.
A computer introduced as a result of a technological breakthrough. Hardware, such as microprocessors, also can be classified in generations. For instance,Intel's Pentium processor line makes up the generation following the company's 80486 CPU (central processing unit) line. Programmers may also refer togenerations of commands, implying a lineage of processes (one process that may give rise to other processes). When users store files in directories and subdirectories, this relation is sometimes expressed in generations (with a grandmother, mother, and daughter directory or file).
Slang term for logging in to a computer or network.
Like a notebook computer, a tablet computer is a portable PC that runs on batteries or AC (alternating current), is 1 or 2 inches thick, and is roughly the width and length of a writing tablet or notebook (8.5 x 11 inches). Although notebook computers typically have an LCD (liquid-crystal display) screen that's attached to the notebook via hinges, a tablet computer typically has a touch-sensitive LCD screen that is part of the main device.
A menu-driven, search-and-retrieval tool that helps Internet users locate information online through menus, which are itemized according to collections of information and stored databases. The menus also may lead to other menus, files, and search tools. Developed at the University of Minnesota in 1991 and named after the school's mascot, the Golden Gophers, Gopher lets users retrieve data over the Internet without using complicated commands and addresses.
A pixel in an LCD (liquid-crystal display) monitor that doesn't work correctly and is always turned on (or stuck as) a certain color, usually red, green, or blue.
A pop-up box that nags the user to update, register, or pay for the software. Nags can occur at random while using the software. Nags can also occur when you start or close the software. Usually, the user must perform some sort of action to close the pop-up box.
A flat disk of silicon crystal sliced from a larger piece. Used in semiconductor chip manufacturing, these disks are approximately 1/30th-inch to 1/50th-inch thick and 3 to 6 inches in diameter. Made to hold circuitry components, wafers are eventually enclosed in another substance, such as plastic or metal.
A virus that travels as a macro embedded in documents, especially Microsoft Word and Excel documents. Such viruses remain dormant until the infected file is opened. Then, if the virus is malicious, the virus may damage other files, perform a prank, or infect other files. Some macro viruses will delete all files in a directory or your entire hard drive. Others are more benign, simply attaching their code to documents. Once an infected file is opened, the virus will usually infect all files that are opened afterward until the virus is removed by software that disinfects the appropriate template file. Macro viruses are quickly spread through email messages or shared files. Antivirus scanning software should be used and updated so macro viruses can be caught before they infect a system.
A method used by some Web sites and marketing companies to track the surfing habits of visitors to their sites. Online profiling is common among shopping sites. It may include noting which products a visitor appears interested in or buys. This data is then used to target products and services to the person visiting the site. The data may be collected with or without the permission and knowledge of visitors to the Web site.
The act of defragmenting information stored in memory, thereby arranging data so the largest free space possible is created.
A tool to convert one language into another that more closely resembles machine code. Translators are also called language processors and include assemblers, compilers, interpreters, and preprocessors.
A key or key combination that executes a specific function or command within an application or operating system. For example, the F7 key in Microsoft Word 6.0 initiates the spelling checker while the F12 key initiates the Save As command. Also called an application shortcut key. A shortcut key can be specified with a specific software package, such as using the ALT key plus the first letter of a pull-down menu option, or it could be a user-created macro.
The act of modifying a piece of hardware or software to perform a function not intended or authorized by the original manufacturer. In gaming, changing a game's code to alter game play; for example, adding new content to existing games, or "total conversion" mods which change the game significantly.
A term for the expected customer feedback after a product's official release. Gamma testing is a play on the term "beta testing", which is the testing software or hardware undergoes before release. Some critics derisively use the term to chastise companies that knowingly release an undertested product, leaving customers to find and report bugs.
A slang expression for a PC that alternates between working and nonworking states. One minute a PC is up and working, the next minute it's down.
A rectangular, flat input device that controls an on-screen cursor by tracing a finger or a stylus across the surface of the tablet. A graphics tablet is used instead of a mouse or trackball when more intricate cursor control is needed, such as when using a drawing or graphics program. Also called a digitizer, digitizing tablet, or drawing tablet.
A circle that represents choices in a common option list form in graphical user interfaces. Only one item in a list with radio buttons can be selected at a time. To select an item in such a list, the user clicks the radio button in front of the desired option, and a dot appears in the circle of the radio button to show the option has been selected. The name radio button comes from the fact that these buttons are similar to those on a radio; choosing one automatically undoes the previous choice.
The term comes from scientific disciplines, where it is most often used as a measurement for the amount of time a radioactive substance takes to lose half of its atoms. In technology, it refers to the amount of time that it takes for a storage device to loose half of its effectiveness.
By altering the headers in an email message, someone with the proper know-how can make an email message appear as if it came from someone or somewhere else.
the protocol most often used to send email) doesn't include much security, making it possible for people to forge, or spoof, the origins of the email.
A section of memory that holds information before it is sent to the monitor. The video buffer also called a screen buffer or regeneration buffer is usually a part of the video card.
Smart Tags are a technology found in Microsoft Office XP. Smart Tags can be used to link portions of a document with other documents or information on the Internet or company intranet. Microsoft was playing with the idea of adding Smart Tags to the next version of Internet Explorer. The plan met with some resistance from Web designers and others who were afraid Microsoft would abuse the Smart Tag technology.
An entry way into a password-protected system that bypasses having to actually use a password. In some systems, designers usually deliberately leave a back door so technicians can enter a system later for maintenance or other purposes.
When one or more of the three-color beams inside a monitor do not align on the screen. This is often seen as a blurring of color onto parts of the monitor that should not have it. Also called convergence error.
A rotating ring usually just behind the focusing ring on a camera. This ring lets you control the amount of light you let into the camera. Only professional-level digital cameras currently have aperture rings.
Usually relating to monitors, the screen pixel resolution and refresh rate the manufacturer recommends for optimal, flicker-free performance.
Vulnerability scanning automatically examines a network for known security holes that could be exploited by outsiders to gain access to a network. The software contains a database of known vulnerabilities and examines a network for these vulnerabilities. Vulnerability scanning is typically employed by companies and corporations looking to close security holes before they're exploited.
The plug at either cable end. One end plugs into the computer, and the other plugs into the device being hooked up to the computer. Connectors are either male (containing pins) or female (containing sockets). The type of cable often determines the shape of the connectors. For example, most cable connectors for mice or keyboards are round, while printer cables have trapezoidal connectors.
When you encrypt a file, you translate the original contents into a code to keep the file secret. Data encryption software uses advanced algorithms to encode a file's contents so they can't be read by anyone who doesn't have the proper key to unscramble them. Encryption algorithms are mathematical, or they apply other rules to files, which systematically change the contents of those files. When children pass secret messages in class, they might use the alphabet replacement method where they write "a" for "b" and "b" for "c" and so on. The shifting of the letters is the algorithm, and nobody could crack the code without knowing which or how many letters were shifted. Encrypting data of any type involves processing a message through an algorithm to scramble it.
A control feature often found in computer or stereo speakers. The balance control adjusts the amount of sound you hear from the right or left speakers. Generally, the balance should be adjusted so that the sound level from both speakers is the same.
An indention at the beginning of a line to signify a new paragraph in a document. Usually about five spaces, tabs are primarily used to ensure equal spacing from line to line. There is also a tab called the write-protect tab on diskettes. When in a certain position, this tab prevents data on the diskette from being overwritten or erased. See 3.5-inch diskette. See 5.25-inch diskette.
To copy a file or files to an alternate location so a safe copy remains if the original is destroyed or damaged. A single file or an entire drive can be backed up if media of sufficient size are available. Because of their large capacity, magnetic tape drives often are used for backing up information. Backup programs often save files in a compressed format that occupies less space on the backup media. This means that to view the backed-up files, the program that backed them up must be used to restore them to their original form. See restore.
To replace a computer component while the computer is on. This ability is especially important for mainframe computers or servers in a client-server system that can't afford downtime. These computers generally have redundant parts, such as hard drives and power supplies, to ensure reliability, and these parts can be switched out if they fail. Storage systems on client-server networks also often use hot swap functions for the same reasons. For personal computers, the advent of the USB (Universal Serial Bus) standard lets users hot swap peripherals into USB ports; the computer automatically recognizes them without rebooting.
An environment on the Internet that prohibits users from accessing specific material or Web sites. Such an environment may not make it impossible to access this information, but it makes it more difficult. For example, in 1999, America Online's Kid's Channel in the United Kingdom created a walled garden to shield children from unsuitable material.
In laser printers, a doctor blade is a straight edge set a precise distance from the developer roller. It ensures that just the right amount of toner sticks to the roller. The doctor blade scrapes away any excess toner.
A printing process in which a printhead heats tiny sections of a colored ribbon to transfer ink to the paper. A dye sublimation printer may use three or four colored ribbons or perhaps a single ribbon with differently colored sections. See thermal transfer printer.
A printed circuit board or adapter that plugs into a computer to add a new function such as modem capabilities or hardware device support. The term also refers to the punched cards used for data storage and entry devices in early computing. See punched card.
A temporary file, document, program, process, or alphanumeric character that is used to hold a place for another file, document, program, process, or character. When the actual information is available, the dummy information is deleted. Dummy is often required as a place holder when a program cannot deal with blank spaces while waiting for data to arrive.
A program package that combines a number of other, seemingly distinct, programs into a single package. Also called integrated software.
A series of characters treated as text. Character strings can contain numbers and letters.
To break into a computer system, typically with the intent to steal or otherwise manipulate information, or to do damage to the system itself.
The ability of a computer to locate and retrieve data immediately from a storage device, without having to start at the beginning and read all the data.
A way of recording CD-ROM discs that adds data in blocks instead of recording the entire disc at once. For example, half of the disc could be written one day and the rest written a few weeks later. Some older CD-ROM drives can't read multisession discs. This type of recording is used by some CD-R (CD-recordable) drives and all CD-RW (CD-rewriteable) drives.
In an image-editing program, this is a technique used to displace colors in an image, giving it an impressionistic look.
A feature that provides step-by-step instructions to lead users through certain tasks in applications. Unlike online help menus, which often must be read before executing a task or printed out, wizards use dialog boxes that walk users through each step of a process. Also can describe an extraordinary programmer.
A term used by Microsoft Excel to describe a spreadsheet file. A workbook can contain numerous spreadsheets in a single file.
The command issued to immediately shut down a Linux system. This command is usually called by issuing the shutdown command.
A glass tube from which all gas has been removed, creating a vacuum. Such tubes containing electrodes for controlling electron flow were used in early computers (before semiconductors) as a switch or an amplifier. Vacuum tubes allowed digital computations at what was then considered a high speed.
Unlike a traditional switch that trips when it is switched, a rocker switch rocks between the on and off positions, hence its name. When one side of the switch is moved to a down position, the other side is always up. Switching on the up side will change the position of the two and trip the switch. You can find rocker switches on many kinds of computers and computer add-ons, including various power devices, surge protectors, monitors, and others.
To place a file that is infected with a virus or otherwise poses a threat in a directory where it cannot do any harm. Functions that divert threatening files to a quarantined directory are typically part of antivirus software.
A packet sent over a network by a system containing information such as the IP (Internet Protocol) address of the system, to indicate the system is ready to receive and transmit data.
A set of hardware normally composed of a keyboard and a monitor that lets users communicate with the internal CPU (central processing unit), which is the "brain" of the computer.
A conductor through which current flows. Batteries, for instance, have two electrodes, the positive electrode is also known as the anode and the negative electrode is known as the cathode.
The absolute minimum length of time required to completely execute a program without introducing new data or extraneous processing.
The process of smoothing, finishing or achieving an extremely close tolerance on the heat-absorbing side of the heatsink, with the idea that heat will transfer more efficiently with a tighter fit between the heatsink and heat-generating component.
To restart the computer and reload the operating system. Many types of computers reboot when the key combination CTRL-ALT-DELETE is pressed. In Windows 95 and newer, rebooting can also be done by selecting Shut Down from the Start menu, then clicking Restart The Computer. Rebooting is sometimes the only way to regain control over a computer that is frozen due to error. Rebooting a computer, however, causes all unsaved data in open applications to be lost.
An error that takes place after starting a computer. This failure usually is caused by a mis-alignment within the computer by the expansions and contractions that occur because of temperature fluctuations when the computer is turned on and off. To avoid this, some users leave the computer running when not in use and only shut off the monitor.
A symbol indicating that the computer is waiting for you to enter information in order to continue.
A setup composed of a computer and peripheral devices that enable someone to do their work. In terms of processing power, workstations fall between personal computers and minicomputers. Also can designate any computer connected to a network.
In computing, 3-D graphics are created by combining numerous triangles to form a desired shape. The term “vertex” typically refers to the individual points or corners of these triangles—the points where two sides of a triangle meet. These vertices are, in fact, the very “virtual matter” that creates a 3-D object.
1,000 floating point operations.
An effect in some digital imaging software programs where algorithms are applied to an image, bending it, and ultimately giving it a spherical shape.
In computers, hybrid refers to a device that is made of two or more technologies. A hybrid computer has both analog and digital capabilities. It uses both analog-to-digital conversion and digital-to-analog conversion so it can read and produce analog and digital data. Robots, for instance, are hybrid computer systems. They accept a command in digital format (the program instructs the machine using binary data) and execute a function in analog format (the robot walks). On the flip side, the robot might use an analog sensor to recognize an object, but it will use a digital computer to process what to do with it. ADCs (analog–to-digital converters) transform factors, such as temperature, motion, pressure, sound, and images, into a binary code the robot can understand.
A glue-like substance specifically designed to connect metal pieces and conduct heat between them. Thermal adhesive is made of substances such as aluminum or silver and is available in syringes or tubes with applicators. Thermal adhesive is not used to connect certain sensitive components; for example, the substance is not intended for attaching a heatsink to a processor.
A hub is a piece of equipment that provides a connection point for a group of computers and peripherals, and it works on a low-level network protocol layer. Just like a wheel on a bicycle, a hub is a central point from which the spokes, or in this case, cables, fan out. Hubs are commonly used in LANs (local-area networks), where two or more computers are sharing the same devices, such as printers, Internet connection, scanners, and so on. The cables for these devices are plugged into ports in the hub. Data is sent to the hub, which then distributes it to other areas on the network. For example, someone working on a computer can send a file to a printer, but that request must be channeled through the hub before it reaches the printer. Most hubs support the Ethernet standard, meaning the hub accepts an Ethernet cable, which also plugs into an NIC (network interface card). There are also non-Ethernet hubs, including Token Ring. A hub can be passive, active, or intelligent. Passive hubs simply accept an electric signal from an incoming packet and broadcast it to the rest of the network. An active hub, sometimes called a repeater, amplifies the signal before sending it to the rest of the network. Amplification guarantees that the signal has enough power to make it throughout the network. An intelligent hub, or manageable hub, is similar to an active hub, but it has extra features. For instance, it provides bridging, routing, and switching and supports remote management and virtual LANs.
The term “hub topology” is used to describe how larger networks are arranged. A hub topology has a main area from which outgoing lines run, and each line has connection ports for attaching devices. ISPs (Internet service providers) use this format for providing access to their subscribers.
One of the largest PDNs (public data networks) in the United States. Telenet serves as the communications backbone for many online services.
The part of a key on the keyboard seen in normal use. Under the plastic keycap marked by a symbol is the actual key, which is a small switch.
A unit of measurement equal to 1,180,591,620,717,411,303,424 bytes, 2 to the 70th power bytes, or roughly 10 to the 21st power. It's also the equivalent of 1,024 exabytes.
A term used to describe computer viruses that exist only in research labs. Used primarily as tools for scientists and programmers, these infectors (estimated to number at least 20,000) make up the majority of existing computer viruses. However, they pose no danger to the public’s computer systems until released “in the wild.
Refers to points along the horizontal and the vertical axes of the computer screen, usually starting in the lower-left corner of the screen. Each pixel (the color dots that make up the screen display) on the display screen has a location on the map of the screen that identifies it to the programs that make the screen addressable (meaning the mouse can tell where it is on the screen and let the application know). Generally, the x-coordinate is the number of pixels going across the screen and the y-coordinate is the number of pixels going up the screen. When the pair intersects, that intersection represents a specific location on the screen.
When programming Web sites and Web-deployed applications, it is common to define the location of the pixel (or set of pixels) in relation to a specific area of the screen. This is the method used to create areas on the screen that will respond to the click or double-click of the mouse. The programmer defines an area that will be sensitive to the mouse activity by outlining the XY coordinates that constitute the boundaries of the area and then linking that area to a URL (uniform resource locator) that contains additional information that the programmer or designer wishes the user to see. Because there are millions of pixels on each screen, the programmer relies on software that creates the coordinate mapping, rather than trying to map each coordinate manually.
This approach creates what’s known as an image map on the Web page. The “map” is really a graphic (it could, in fact, be an image of an actual map) with its coordinates mapped and with sets of coordinates linked to other html (Hypertext Markup Language) pages. The image map thus serves as a sort of menu. For example, in the case of a mapped picture of an actual United States map, clicking on one state might take the user to information about that state, while clicking on another state takes the user to a different page. The image could also simply be a product photo that links to information about a product
A FTP (File Transfer Protocol) that works over phone lines and is noted for its relatively slow speed and high accuracy. Most communications programs allow users to select Kermit as the protocol for a specific transfer or as the default protocol for all transfers.
A technically sophisticated user who spends a lot of time at a computer. It refers to a person who writes computer programs, "hacking" up the digital code. Hacker is often erroneously used, instead of cracker, to refer to those who illegally break into computer systems to do damage, steal secrets, or enter simply because they can.
Another term for the data bus that runs between the (CPU) central processing unit and the L2 (level 2) cache memory. The backside bus is typically faster than the frontside bus because cache memory usually offers faster access times than system memory, allowing the bus to closer approximate the speed of the CPU.
A wire that is one nanometer (one thousandth of one millimeter) thick. Nanowires are used as semiconductors, barcodes, and LEDs (light-emitting diodes), depending on their chemical composition.
The nastiest form of nastygram, an ill-tempered, malicious, or disapproving e-mail message, has its roots in Unix systems, where users on different terminals share one large computer.
It was possible to send e-mail containing computer code that would freeze up the recipient’s terminal or computer or execute as a program in order to do something prankish or even damaging. Known as letterbombs, these nastygrams were the ancestors of the modern e-mail attacks that try to trick recipients into downloading and running attached virus programs.
The term also refers to a more formal and legitimate style of unwanted e-mail in the form of a rebuke from an online authority. An example would be a warning for breaking some rule of a newsgroup or e-mail list, such as an off-topic posting or letting an argument get out of hand.
Programmers have sometimes used the term nastygram to refer to an e-mail message that expresses dissatisfaction or criticism from a client or from superiors within the company. In this context, nastygram carries the connotation of criticism that’s overly nitpicky or otherwise unfair.
Less commonly, nastygram may refer to automated unpleasant e-mail, such as bounce notices to let you know that an e-mail message you sent is undeliverable. But as mail handling robots have no ill will in their messages, however unwelcome they may be, the reference to automatic mail as nastygrams is often facetious.
A metric prefix meaning ten thousand. A myriabyte would be 10KB or 0.01MB. The symbols for myria are ma or my.
Sony Philips Digital Interface Format A type of interface used to connect a variety of electrical components, primarily audio devices.
Advanced Technology Attachment Packet Interface (ATAPI)
An extension to the EIDE (Enhanced IDE) interface that supports CD-ROM and tape drives, which were left out of the original EIDE and IDE standards. Also known as Fast AT Attachment (Fast ATA), this is an updated version of the Integrated Drive Electronics (IDE) storage interface that works with hard drives and CD-ROM drives. It can shuttle data to and from the drive three to four times faster than the IDE standard (transferring data between 11MB and 16.6MB per second) and can support data storage devices that store up to 8GB more than IDE drives. Also known as ATA (Advanced Technology Attachment), the EIDE standard lets storage devices, such as hard drives and CD-ROM drives, connect to computers. Initially, EIDE supported drives of approximately 8GB in size, and it supported data speed rates between 11MBps (megabytes per second) and 16.6MBps. Once the 8GB limit was overcome by better support from a PC’s BIOS (Basic Input/Output System; the underlying software that lets a PC use basic hardware), the theoretical limit for ATA drives became 137GB, but users can expect this limit will be breached, just like all the others. Currently, the largest ATA or EIDE drives are about 120GB in size.
EIDE is an upgrade to the older IDE (or Advanced Technology Attachment) standard, which supported drives of 528MB and was only one-third to one-fourth as fast as first-generation EIDE. The primary competitor to the EIDE standard is SCSI (Small Computer System Interface), which is common in Apple computers; SCSI generally allows greater speeds, but it is expensive and more difficult to use. The latest descendents of the standard are Ultra ATA-66, which offers speeds up to 66MBps, and Ultra ATA-100, which offers speeds up to 100MBps. Also, keep on the lookout for Serial ATA, a new standard that should offer even greater speeds.
A new interface for internal devices such as hard drives, debuting in 2002. Serial ATA, initially having a theoretical maximum throughput of 150MBps, allows better signal timing and higher speeds than the parallel EIDE standards such as Ultra ATA/133/100/66. SATA also enables easier device setup and better airflow within the computer case with less obstructive data cables. Industry analysts expect SATA eventually to supplant EIDE.
An electronic component used for RAM and fast data switching. CMOS semiconductors are made of two metal-oxide field effect transistors for high speed and low power use. However, they can be damaged by static electricity. (Pronounced see-moss.) A type of computer chip that requires very little power. This makes it particularly suitable for use in notebook computers, which need to get as much life as possible out of each battery charge, and for the computer memory holding system startup information.
PCs contain a CMOS memory chip that stores information the computer needs each time it boots up. This includes things such as the date and time, as well as information about the system configuration—how many disk drives and what kind, how much memory, what type of processor, and so on. Without this information, a computer is very limited in how it can operate.
Computer memory requires power, so most memory empties out when a computer is powered down. Because the CMOS chip requires so little power, it is run continuously off a battery inside the computer. A single battery is usually enough to power the CMOS for the life of the computer. Therefore, whenever the computer is powered on, the information in the CMOS can load right in for immediate use by the computer's BIOS (Basic Input/ Output System).
When you turn on your computer, you usually see a lot of information flash on the screen about memory, video card in use, etc. The computer is actually running diagnostic tests on its components and initializing those components for use, based on information pulled up from the CMOS.
In DVDs, a chapter is each independent section on the disc. This can be compared to tracks on CDs.
A type of programming language used to create software for more than one type of computer system.
The x coordinate on an (x, y) graph. See Ordinate.
A device that lets a cable be attached to a device that requires slightly different wire connections.
An International System of Units (SI) prefix meaning one quadrillionth, or 10 to the negative 15th power. For example, a femtosecond would be one quadrillionth of a second, or 1/1,000,000,000,000,000th of a second. The symbol for femto- is f.
The placement of one object within another. In computing, this refers to the placement of a graphic in a word processing document or a text document within a database. A set of instructions also can be nested in another set of instructions or within a document activated when selected. Programmers also can nest programming loops within other programming loops.
A Web camera positioned in the coffin of a deceased person. The term comes from the Dutch film of the same name, which used the idea as a way to comment on the extremes to which technology can lead us.
In telephone systems, a trunk is a connection between two main switching stations. The trunk carries several lines of voice and data transmissions simultaneously.
To end a session with a program by purposely closing the application.
A quality attributed to anything that seems to be everywhere at all times. Often used in technology circles to describe technologies in widespread use. Some may say mobile phones, for instance, are ubiquitous.
A data transmission standard developed in the late 1960s by Norman Abramson and a team of researchers at the University of Hawaii. Using TDMA (time division multiple access) technology, Aloha transmitted data in packets containing addressing information, and in the event of a collision the data was retransmitted. Aloha was the basis for Alohanet, a precursor to the Ethernet network standard.
A communications device, such as a modem, that can transmit and receive signals from distances of more than one mile. Most modems are long-haul modems. Compare to short-haul.
A wiki is a type of collaborative blog. Instead of one author providing and editing content, any user can post content and edit the content of others.
Computers are obviously good at crunching numbers and allowing for detailed simulations. Until Mathematica was released in 1988, however, no single program could harness all that power and let scientists, engineers, theorists, and programmers bend it to their will. Individual applications were available before then that were designed to perform specific tasks, but Mathematica let just about anybody do just about anything math-related.
Stephen Wolfram designed Mathematica and Wolfram Research, a company he founded in 1987. The software completely revolutionized the field of technical computing, providing users with a single package that could perform practically any mathematical calculation. From physics calculations and astronomical star charts to electrical circuit design and economics equations, if it involves numbers, Mathematica can handle it. From the very beginning, Mathematica could handle symbolic equations and had powerful graphing abilities, and the product has improved steadily over the years, adding more features while retaining its ease-of-use. The core of the software is a powerful programming language that lets users write programs in a variety of ways. Several add-on packages also are available that give people in specific fields tools they can use to do their jobs more efficiently. Optica, for example, is a package that makes it easy to solve optical engineering problems without having to write any fundamental programs to get started. The software also links directly into other programs, such as Microsoft Excel, letting users apply Mathematica’s power to nearly any other application that involves numbers. It can even be integrated into Web pages to create interactive graphs and calculations. This connectivity works both ways, as output from Mathematica can be easily sent to an external program, such as an application designed to render high-resolution 3D graphs.
More than 20,000 copies of Mathematica were sold within months of its original release, and the number of users today has expanded into the millions. Professionals now view the software as an indispensable tool, and students use it in many high school and college math courses. An ever-increasing number of Web designers use an offshoot of the original software, webMathematica, to add interactive calculations to their sites.
A cast of pixels on a monitor that appear as small, white, flickering dots. Snow can be caused by simple interference or by conflicts within the video memory.
To turn on the computer after it has been shut off. Also called cold start. Compare to warm boot. See boot.
Software or hardware that once was included with several other products (a bundle) but was removed from the packaging or is sold separately. For example, games and word processing applications often are bundled with new computers and included in the price. When the product is sold separately, however, it is considered unbundled. Compare to bundled software.
A signal from an Ethernet device alerting all other devices that a collision has occurred and to stop transmitting. The purpose of a jam is to clear the network's data transmission lines and have all devices begin attempting to send data again. See collision.
Texture element. The smallest component of a texture in a 3-D image.
A printing mechanism shaped like a round disk with a number of spokes, or arms, that extend from its center. Each arm has a fully formed character on its tip. The arm hits the ribbon, and the impact makes a mark on the paper. One daisywheel contains all the characters for one font only; a change in fonts requires a different daisywheel. Daisywheels are found on a daisywheel printer. Also called print wheel.
Software or hardware that limits or restricts certain kinds of computer access from a network or other outside source. A router is a good example of a hardware device that often has a built-in firewall. Firewalls are used to thwart would-be hackers from infiltrating computer systems. See hacker.
A pen-like scanning device, a wand is commonly used with such hardware peripherals as bar code readers. Also used to describe a stylus used with graphics tablets. To scan text with a wand, a user passes the tip of the wand over text; the optical scanning mechanism in the wand takes the text it has "read" and passes it along to the computer for processing.
Metadata is technically data about data. NTFS (NT file system) uses the concept of metadata frequently. In NTFS metadata maintains information about the various files on the system including a file's location on the hard drive, file name, and security information. Metadata may also track information about the hard drive in general. For instance, bad clusters that can no longer reliably hold information are tracked using metadata. Most metadata resides in the Master File Table or MFT although, technically, the MFT itself is a metadata file. Media metadata is a type of metadata many users may recognize. For instance, an MP3's (Moving Pictures Experts Group Audio Layer 3's) metadata may contain information such as song title, artist, and album. This data is visible in most media players as well as in the file's properties. See NT file system (NTFS).
A plastic ring that fits into a reel of magnetic tape to prevent its files from being overwritten or erased. See file protect ring.
A number that allows plug-and-play systems to identify an added device and configure it properly. The number indicates the device's manufacturer, model, and version number.
A command or option that will let users leave and close a program. It may require a special keystroke or key combination in a DOS program, or it may require users to select the Exit option from the File menu in a Windows program.
To restore files from an archive or backup to their original location, usually a hard drive. Compare to archive file.
To compress data, or "smash" it together by taking out excess space, so it occupies less space when stored or transmitted. Compressed data must be decompressed before it can be used again. Compare to unpack. See data compression.
Although an unsophisticated user tends to denounce any type of unreadable images that appear on his screen as garbage, the true definition of garbage is meaningless, unnecessary data the computer places in the RAM. Garbage collection is a system for automatically reclaiming this storage space in programs, ensuring that systems aren't needlessly tied up by preserving RAM data that is no longer needed (The failure to clean up memory that is no longer being used is called a memory leak). Such garbage collection, which frees programmers from having to write software that explicitly requests storage and returns it to the system when no longer needed, is also known as automatic storage (or memory) allocation.
A garbage collection program must first identify unneeded data and then make the storage area it occupies available for use by the computer again. An object in a program is considered live if the program might access that object in the future. If not, the object is considered dead. Many garbage collection programs consider a given object dead if the program has eliminated all pointers to it. Some programs keep track of the pointers on each object and designate it dead when the count falls to zero. Others keep track of which objects are considered live and eliminate dead objects not within that group.
Early garbage collection programs only kicked in after the amount of memory used reached a particular limit. Once across that threshold, the program would pause to examine all its memory, causing delays. More modern garbage collection programs kick in every time memory is allocated or when there are pauses in activity. It was first developed for languages such as LISP (list processing), a high-level programming language developed in 1960 for use in artificial intelligence applications that computes with symbolic expressions rather than numbers. Such garbage collection programs were also used with the language SNOBOL (String Oriented Symbolic Language), an early list-processing language developed in the early 1960s. More recently, it has appeared in embedded languages such as PostScript and object-oriented languages such as Java.
The third definition for garbage centers on a widely used acronym within the computer industry GIGO (garbage in, garbage out). That admonition warns all computer users that, no matter how advanced the machine, inputting faulty or substandard information will only result in more problematic data. Another interpretation of the term is garbage in, gospel out, warning users against placing too much faith in computers that may be handling faulty data.
An error that occurs during the transfer of data.