Select any of the letters to jump directly to an alphabetical listing of terms.

Access provider is any organization that arranges for an individual or an organization to have access to the Internet. Access providers are generally divided into two classes: Internet access providers (ISPs) and online service providers (OSPs). ISPs can be local businesses that pay for a high-speed connection to one of the companies (such as AT&T, Sprint, or MCI in the U.S.) that are part of the Internet. They can also be national or international companies that have their own networks (such as AT&T's WorldNet or IBM's Global Services). OSPs, sometimes just called "online services," also have their own networks but provide additional information services not available to non-subscribers America Online is the most successful example of an OSP.

algorithm - The term algorithm (pronounced AL-go-rith-um) is a procedure or formula for solving a problem. The word derives from the name of the mathematician, Mohammed ibn-Musa Al-Khowarizmi, who was part of the royal court in Baghdad and who lived from about 780 to 850. Al-Khowarizmi's work is the likely source for the word algebra as well. A computer program can be viewed as an elaborate algorithm. In mathematics and computer science, an algorithm usually means a small procedure that solves a recurrent problem.

alternate newsgroup - "alt." is the prefix for any of the hundreds of "alternate" user-originated newsgroups that are part of Usenet. Like other newsgroups, each "alt." newsgroup is arranged in a hierarchy of topical discussion boards that you may read or post to. "alt" is one of many major newsgroups; others include: news, rec (recreation), comp (computers), and soc (social). The "alt" newsgroups are known (and used most frequently) for their alt.sex and related categories, but are also known for including a wide and inventive range of discussion topics.

ampere - An ampere is a unit of measure of the rate of electron flow or current in an electrical conductor. One ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) moving past a specific point in one second. Physicists consider current to flow from relatively positive points to relatively negative points; this is called conventional current or Franklin
current. The ampere is named after Andre Marie Ampere, French physicist (1775-1836).

analog-to-digital conversion is an electronic process in which a continuously variable (analog) signal is changed, without altering its essential content, into a multi-level (digital) signal. The input to an analog-to-digital converter (ADC) consists of a voltage that varies among a theoretically infinite number of values. Examples are sine waves, the waveforms representing human speech, and the signals from a conventional television camera. The output of the ADC, in contrast, has defined levels or states. The number of states is almost always a power of two -- that is, 2, 4, 8, 16, etc. The simplest digital signals have only two states, and are called binary. Digital signals propagate more efficiently than analog signals, largely because digital impulses, which are well-defined and orderly, are easier for electronic circuits to distinguish from noise, which is chaotic. This is the chief advantage of digital modes in communications. Computers "talk" and "think" in terms of binary digital data; while a microprocessor can analyze analog data, it must be converted into digital form for the computer to make sense of it.

Antivirus (or "anti-virus") software is a class of program that searches your hard drive and floppy disks for any known or potential viruses. The market for this kind of program has expanded because of Internet growth and the increasing use of the Internet by businesses concerned about protecting their computer assets.

Asimov's Three Laws of Robotics - Science-fiction author Isaac Asimov is often given credit for being the first person to use the term robotics in a short story composed in the 1940s. In the story, Asimov suggested three principles to guide the behavior of robots and smart machines. Asimov's Three Laws of Robotics, as they are called, have survived to the present:

1. Robots must never harm human beings.
2. Robots must follow instructions from humans without violating rules.
3. Robots must protect themselves without violating the other rules.

Assembler - is a program that takes basic computer instructions and converts them into a pattern of bits that the computer's processor can use to perform its basic operations. Some people call these instructions assembler language and others use the term assembly language.

AVI - (Audio Video Interleaved) file is a sound and motion picture file that conforms to the Microsoft Windows Resource Interchange File Format (RIFF) specification. AVI files (which end with an .avi extension) require a special player that may be included with your Web browser or may require downloading.

Backup is the activity of copying files or databases so that they will be preserved in case of equipment failure or other catastrophe. Backup is usually a routine part of the operation of large businesses with mainframes as well as the administrators of smaller business computers. For personal computer users, backup is also necessary but often neglected. The retrieval of files you backed up is called restoring them.

Bandwidth (the width of a band of electromagnetic frequencies) is used to mean (1) how fast data flows on a given transmission path, and (2), somewhat more technically, the width of the range of frequencies that an electronic signal occupies on a given transmission medium. Any digital or analog signal has a bandwidth. Generally speaking, bandwidth is directly proportional to the amount of data transmitted or received per unit time. In a qualitative sense, bandwidth is proportional to the complexity of the data for a given level of system performance. For example, it takes more bandwidth to download a photograph in one second than it takes to download a page of text in one second. Large sound files, computer programs, and animated videos require still more bandwidth for acceptable system performance. Virtual reality (VR) and full-length three-dimensional audio/visual presentations require the most bandwidth of all. In digital systems, bandwidth is expressed as data speed in bits per second (bps). Thus, a modem that works at 57,600 bps has twice the bandwidth of a modem that works at 28,800 bps.

Beta test - In software development, a beta test is the second phase of software testing in which a sampling of the intended audience tries the product out. (Beta is the second letter of the Greek alphabet.) Originally, the term alpha test meant the first phase of testing in a software development process. The first phase includes unit testing, component testing, and system testing. Beta testing can be considered "pre-release testing."

Binary describes a numbering scheme in which there are only two possible values for each digit: 0 and 1. The term also refers to any digital encoding/decoding system in which there are exactly two possible states. In digital data memory, storage, processing, and communications, the 0 and 1 values are sometimes called "low" and "high," respectively. Binary numbers look strange when they are written out directly. This is because the digits' weight increases by powers of 2, rather than by powers of 10. In a digital numeral, the digit furthest to the right is the "ones" digit; the next digit to the left is the "twos" digit; next comes the "fours" digit, then the "eights" digit, then the "16s" digit, then the "32s" digit, and so on. The decimal equivalent of a binary number can be found by summing all the digits. For example, the binary 10101 is equivalent to the decimal 1 + 4 + 16 = 21

Binary File is a file whose content must be interpreted by a program or a hardware processor that understands in advance exactly how it is formatted. That is, the file is not in any externally identifiable format so that any program that wanted to could look for certain data at a certain place within the file. A progam (or hardware processor) has to know exactly how the data inside the file is laid out to make use of the file. In general, executable (ready-to-run) programs are often identified as binary files and given a file name extension of ".bin". Programmers often talk about an executable program as a "binary" and will ask another programmer to "send me the binaries." (A synonym for this usage is object code.) A binary file could also contain data ready to be used by a program. In terms of transmitting files from one place to another, a file can be transmitted as a "binary," meaning that the programs handling it don't attempt to look within it or change it, but just pass it along as a "chunk of 0s and 1s," the meaning of which is unknown to any network device.

BinHex is a utility for converting (encoding) Macintosh files into files that will travel well on networks either as files or e-mail attachments. Like Uuencode, BinHex encodes a file from its 8-bit binary or bit-stream representation into a 7-bit ASCII set of text characters. The recipient must decode it at the other end. Older e-mail utilities sometimes can't handle binary transmissions so text encoding ensures that a tranmission will get to an older system. BinHex specifically handles both resource and data forks in Macintosh files (which Uuencode doesn't). BinHex files have a suffix of ".hqx".

Bit (short for binary digit) is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1. Although computers usually provide instructions that can test and manipulate bits, they generally are designed to store data and execute
instructions in bit multiples called bytes. In most computer systems, there are eight bits in a byte. The value of a bit is usually stored as either above or below a designated level of electrical charge in a single capacitor within a memory device.

Bit map (often spelled "bitmap") defines a display space and the color for each pixel or "bit" in the display space. A Graphics Interchange Format and a JPEG are examples of graphic image file types that contain bit maps. A bit map does not need to contain a bit of color-coded information for each pixel on every row. It only needs to contain information indicating a new color as the display scans along a row. Thus, an image with much solid color will tend to require a small bit map. Because a bit map uses a fixed or raster graphics method of specifying an image, the image cannot be immediately rescaled by a user without losing definition. A vector graphics graphic image, however, is designed to be quickly rescaled. Typically, an image is created using vector graphics and then, when the artist is satisifed with the image, it is converted to (or saved as) a raster graphic file or bit map.

Bits per second (abbreviated bps) is a common measure of data speed for computer modem and transmission carriers. As the term implies, the speed in bps is equal to the number of bits transmitted or received each second. The duration d of a data bit, in seconds, is inversely proportional to the digital transmission speed s in bps:

d = 1/s

Larger units are sometimes used to denote high data speeds. One kilobit per second (abbreviated Kbps in the U.S.; kbps elsewhere) is equal to 1,000 bps. One megabit per second (Mbps) is equal to 1,000,000 bps or 1,000 kbps. Computer modems for twisted pair telephone lines usually operate at speeds between 14.4 and 57.6 kbps. The most common speeds are 28.8 and 33.6 kbps. So-called "cable modems," designed for use with TV cable networks, can operate at more than 100 kbps. Fiberoptic modems are the fastest of all; they can send and receive data at many Mbps.

Bloviate (pronounced BLOW-vee-ayt) is to speak or write overexpansively or with undue grandiosity. It suggests a derivation from to blow, meaning to boast. The term has gained some currency through distribution over Web chat forums and on Web sites.

Blue Screen of Death is a rather terrifying display image containing white text on a blue background that is generated by Windows operating systems when the system has suddenly terminated with an error. The system is locked up and must be restarted.

Bookmark - Using a World Wide Web browser, a bookmark is a saved link to a Web page that has been added to a list of saved links. When you are looking at a particular Web site or home page and want to be able to quickly get back to it later, you can create a bookmark for it. You can think of your browser as a book full of (millions of ) Web pages and a few well-placed bookmarks that you have chosen. The list that contains your bookmarks is the "bookmark list".

Buffer is a data area shared by hardware devices or program processes that operate at different speeds or with different sets of priorities. The buffer allows each device or process to operate without being held up by the other. In order for a buffer to be effective, the size of the buffer and the algorithms for moving data into and out of the buffer need to be considered by the buffer designer. Like a cache, a buffer is a "midpoint holding place" but exists not so much to accelerate the speed of an activity as to support the coordination of separate activities.

Bug - is a coding error in a computer program. (Here we consider a program to also include the microcode that is manufactured into a microprocessor.) The process of finding bugs before program users do is called debugging. Debugging starts after the code is first written and continues in successive stages as code is combined with other units of programming to form a software product, such as an operating system or an application. After a product is released or during public beta testing, bugs are still apt to be discovered. When this occurs, users have to either find a way to avoid using the "buggy" code or get a patch from the originators of the code.

Burn (verb) a CD-ROM is a colloquial term meaning to write to the CD-ROM all the content that is to be put on it for a given purpose. After you've burned or burnt (either is correct) the CD-ROM, copies can be made one at a time or in multiples (the latter process is usually called duplication or replication).

Bus is a transmission path on which signals are dropped off or picked up at every device attached to the line. Only devices addressed by the signals pay attention to them; the others discard the signals. According to Winn L. Rosch, the term derives from its similarity to autobuses that stop at every town or block to drop off or take on riders. In general, the term is used in two somewhat different contexts: (1) A bus is a network topology or circuit arrangement in which all devices are attached to a line directly and all signals pass through each of the devices. Each device has a unique identity and can recognize those signals intended for it. (2) In a computer, a bus is the data path on the computer's motherboard that interconnects the microprocessor with attachments to the motherboard in expansion slots (such as hard disk drives, CD-ROM drives, and graphics adapters).

Byte is a unit of data that is eight binary digits long. A byte is the unit most computers use to represent a character such as a letter, number, or typographic symbol (for example, "g", "5", or "?"). A byte can also hold a string of bits that need to be used in some larger unit for application purposes (for example, the stream of bits that constitute a visual image for a program that displays images or the string of bits that constitutes the machine code of a computer program).

Cable modem is a device that enables you to hook up your PC to a local cable TV line and receive data at about 1.5 Mbps. This data rate far exceeds that of the prevalent 28.8 and 56 Kbps telephone modems and the up to 128 Kbps of Integrated Services Digital Network (ISDN) and is about the data rate available to subscribers of Digital Subscriber Line (DSL) telephone service. A cable modem can be added to or integrated with a set-top box that provides your TV set with channels for Internet access. In most cases, cable modems are furnished as part of the cable access service and are not purchased directly and installed by the subscriber.

CAD (computer-aided design) software is used by architects, engineers, drafters, artists, and others to create precision drawings or technical illustrations. CAD software can be used to create two-dimensional (2-D) drawings or three-dimensional (3-D) models.

CAD/CAM (computer-aided design/computer-aided manufacturing) is software used to design products such as electronic circuit boards in computers and other devices.

CD burner is the informal name for a CD recorder, a device that can record data to a compact disc. CD-Recordable (CD-R) and CD-Rewritable (CD-RW) are the two most common types of drives that can write CDs, either once (in the case of CD-R) or repeatedly (in the case of CD-RW). In the recording process, the data is actually etched into the disc (burned) with a laser, as compared with non-recordable CDs. Audio CDs and CD-ROMs are pressed from copies of the original recordings (which are burned by lasers). Since the non-recordable CDs are manufactured in this manner, they can not be written, or rewritten in a desktop environment.

Clip art - frequently used in desktop publishing before the arrival of the Web, is"canned" artwork designed for use in publications or Web pages by artists or non-artists . The use of clip art can save artists time and make art both possible and economical for non-artists. Clip art includes both subject-related illustrations and visual elements such as horizontal lines, bullets, and text separators.

Clock speed refers to the number of pulses per second generated by an oscillator that sets the tempo for the processor. Clock speed is usually measured in MHz (megahertz, or millions of pulses per second) or GHz (gigahertz, or billions of pulses per second). Today's personal computers run at a clock speed in the hundreds of megahertz and some exceed one gigahertz. The clock speed is determined by a quartz-crystal circuit, similar to those used in radio communications equipment. Computer clock speed has been roughly doubling every year. The Intel 8088, common in computers around the year 1990, ran at 4.77 MHz. The 1 GHz mark was passed in the year 2000.

Coaxial cable is the kind of copper cable used by cable TV companies between the community antenna and user homes and businesses. Coaxial cable is sometimes used by telephone companies from their central office to the telephone poles near users. It is also widely installed for use in business and corporation Ethernet and other types of local area network. Coaxial cable is called "coaxial" because it includes one physical channel that carries the signal surrounded (after a layer of insulation) by another concentric physical channel, both running along the same axis. The outer channel serves as a ground. Many of these cables or pairs of coaxial tubes can be placed in a single outer sheathing and, with repeaters, can carry information for a great distance. Coaxial cable was invented in 1929 and first used commercially in 1941. AT&T established its first cross-continental coaxial
transmission system in 1940. Depending on the carrier technology used and other factors, twisted pair copper wire and optical
fiber are alternatives to coaxial cable.

Compact disc - A compact disc [sometimes spelled disk] (CD) is a small, portable, round medium made of molded polymer (close in size to the floppy disk) for electronically recording, storing, and playing back audio, video, text, and other information in digital form. Tape cartridges and CDs generally replaced the phonograph record for playing back music. At home, CDs have tended to replace the tape cartridge although the latter is still widely used in cars and portable playback devices. Initially, CDs were read-only, but newer technology allows users to record as well. CDs will probably continue to be popular for music recording and playback. A newer technology, the digital versatile disc (DVD), stores much more in the same space and is used for playing back movies.

Compiler - A compiler is a special program that processes statements written in a particular programming language and turns them into machine language or "code" that a computer's processor uses. Typically, a programmer writes language statements in a language such as Pascal or C one line at a time using an editor. The file that is created contains what are called the source statements. The programmer then runs the appropriate language compiler, specifying the name of the file that contains the source statements.

CCTV (closed circuit television) is a television system in which signals are not publicly distributed; cameras are connected to television monitors in a limited area such as a store, an office building, or on a college campus. CCTV is commonly used in surveillance systems.

CERN - the high-energy particle physics laboratory in Geneva, Switzerland, is where, in 1991, a researcher, Dr. Tim Berners-Lee, essentially invented the World Wide Web. Berners-Lee is credited with developing the idea of combining hypertext with the speed of today's electronic networks. Working with a small team, he developed the Hypertext Transfer Protocol (HTTP) on which the Web is based.

Data is information that has been translated into a form that is more convenient to move or process. Relative to today's computers and transmission media, data is information converted into binary digital form.

Database is a collection of data that is organized so that its contents can easily be accessed, managed, and updated. The most prevalent type of database is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object-oriented programming database is one that is congruent with the data defined in object classes and subclasses.

Debugging is the process of locating and fixing or bypassing bug (errors) in computer program code or the engineering of a hardware device. To debug a program or hardware device is to start with a problem, isolate the source of the problem, and then fix it.

Decompile is to convert executable (ready-to-run) program code (sometimes called object code) into some form of higher-level programming language so that it can be read by a human. Decompilation is a type of reverse engineering that does the opposite of what a compiler does. The tool that accomplishes this is called a decompiler. A similar tool, called a disassembler, translates object code into assembler language. There are a number of different reasons for decompilation or disassembly, such as understanding a program, recovering the source code for purposes of archiving or updating, finding viruses, debugging programs, and translating obsolete code.

Decompressing is the act of expanding a compression file back into its original form. Software that you download from the Internet often comes in a compressed package that can uncompress itself when you click on it. You can also uncompress files using popular tools such as PKZIP in the DOS operating system, WinZip in Windows, and MacZip in Macintosh.

Dedicated hosting - In the Web hosting business, a dedicated server refers to the rental and exclusive use of a computer that includes a Web server, related software, and connection to the Internet, housed in the Web hosting company's premises. A dedicated server is usually needed for a Web site (or set of related company sites) that may develop a considerable amount of traffic - for example, a site that must handle up to 35 million hits a day.

Default is a predesigned value or setting that is used by a computer program when a value or setting is not specified by the program user. The program user can be either an interactive user of a graphical user interface or command line interface, or a programmer using an application program interface. When the program receives a request from an interactive user or another program, it looks at the information that has been passed to it. If a particular item of information is not specified in the information that is passed, the program uses the default value that was defined for that item when the program was written. In designing a program, each default is usually preestablished as the value or setting that most users would probably choose.

Defragmentation is the process of locating the noncontiguous fragments of data into which a computer file may be divided as it is stored on a hard disk, and rearranging the fragments and restoring them into fewer fragments or into the whole file. Defragmentation reduces data access time and allows storage to be used more efficiently. "Defrag" is a short form of the verb to defragment and sometimes the name of the utility used for defragementing, which is also called a defragmenter.

Degauss (pronounced dee-GOWS) is to demagnetize. Degaussing a computer display removes any undesirable magnetic field that may have built up within the display, causing distortion of the image or color. Display monitors with cathode ray tube (CRT) technology are subject to the buildup of magnetic fields. Many display manufacturers include an internal coil that will degauss the display when it is turned on. Some displays also include an external control that a user can operate to degauss the display at any time. Degaussing a magnetic storage medium removes all the data stored on it. A degausser is a device used for this purpose.

Desktop is a computer display area that represents the kinds of objects one might find on a real desktop: documents, phonebook, telephone, reference sources, writing (and possibly drawing) tools, project folders. A desktop can be contained in a window that is part of the total display area or can be "full-screen" (the total display area).

Device driver - a program that controls a particular type of device that is attached to your computer. There are device drivers for printers, displays, CD-ROM readers, diskette drives, and so on.

Dial-up pertains to a telephone connection in a system of many lines shared by many users. A dial-up connection is established and maintained for a limited time duration. The alternative is a dedicated connection, which is continuously in place. Dial-up lines are sometimes called switched lines and dedicated lines are called nonswitched lines. A dedicated line is often a leased line that is rented from a telephone company.

Digital describes electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is expressed or represented by the number 1 and non-positive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0's and 1's. Each of these state digits is referred to as a bit (and a string of bits that a computer can address individually as a group is a byte). Prior to digital technology, electronic transmission was limited to analog technology, which conveys data as electronic signals of varying frequency or amplitude that are added to carrier waves of a given frequency. Broadcast and phone transmission has conventionally used analog technology. Digital technology is primarily used with new physical communications media, such as satellite and fiber optic transmission. A modem is used to convert the digital information in your computer to analog signals for your phone line and to convert analog phone signals to digital information for your computer.

Direct access is the ability to obtain data from a storage device by going directly to where it is physically located on the device rather than by having to sequentially look for the data at one physical location after another. A direct access storage device (DASD) has the electrical or electromechanical means to be immediately positioned for reading and writing at any addressable location on the device.

Directory is, in general, an approach to organizing information, the most familiar example being a telephone directory.
1) On the World Wide Web, a directory is a subject guide, typically organized by major topics and subtopics. The best-known directory is the one at Yahoo (http://www.yahoo.com). Many other sites now use a Yahoo-like directory including major portal sites.
2) In computer file systems, a directory is a named group of related file that are separated by the naming convention from other groups of files.
3) In computer networks, a directory is a collection of users, user passwords, and, usually, information about what network resources they can access.

Diskette is a random access, removable data storage medium that can be used with personal computers. The term usually refers to the magnetic medium housed in a rigid plastic cartridge measuring 3.5 inches square and about 2 millimeters thick. Also called a "3.5-inch diskette," it can store up to 1.44 megabytes (MB) of data.

Distributed learning is a general term used to describe a multi-media method of instructional delivery that includes a mix of Web-based instruction, streaming video conferencing, face-to-face classroom time, distance learning through television or video, or other combinations of electronic and traditional educational models. Although distributed learning can be executed in a variety of ways, it is consistent in that it always accomodates a separation of geographical locations for part (or all) of the instruction, and focuses on learner-to-learner as well as instructor-to-learner interaction.

Display modes - The term display mode refers to the characteristics of a computer display, in particular the maximum number of colors and the maximum image resolution (in pixels horizontally by pixels vertically). The earliest displays for personal computers were monochrome monitors that were used in word processors and text-based computer systems in the 1970s. In 1981, IBM introduced the Color Graphics Adapter (CGA). This display system was capable of rendering four colors, and had a maximum resolution of 320 pixels horizontally by 200 pixels vertically. While CGA was all right for simple computer games such as solitaire and checkers, it did not offer sufficient image resolution for extended sessions of word processing, desktop publishing, or sophisticated graphics applications.

In 1984, IBM introduced the Enhanced Graphics Adapter (EGA) display. It allowed up to 16 different colors and offered resolution of up to 640 x 350. This improved the appearance over earlier displays, and made it possible to read text easily. Nevertheless, EGA did not offer sufficient image resolution for high-level applications such as graphic design and desktop publishing.

In 1987, IBM introduced the Video Graphics Array (VGA) display system. This has become the accepted minimum standard for PCs. Some VGA monitors are still in use today. The maximum resolution depends on the number of colors displayed. You can choose between 16 colors at 640 x 480, or 256 colors at 320 x 200.

In 1990, IBM intoduced the Extended Graphics Array (XGA) display as a successor to its 8514/A display. A later version, XGA-2 offers 800 x 600 pixel resolution in true color (16 million colors) and 1024 x 768 resolution in 65,536 colors. These two image resolution levels are perhaps the most popular in use today by individuals and small businesses.

The Video Electronics Standards Assocation (VESA) has established a standard programming interface for Super Video Graphics Array (SVGA) displays, called the VESA BIOS Extension. Typically, an SVGA display can support a palette of up to 16,000,000 colors.

Recently, new specifications have arisen. These include Super Extended Graphics Array (SXGA) and Ultra Extended Graphics Array (UXGA). The SXGA specification is generally used in reference to screens with 1280 x 1024 resolution; UXGA refers to a resolution of 1600 by 1200.

Dithering is the attempt by a computer program to approximate a color from a mixture of other colors when the required color is not available. For example, dithering occurs when a color is specified for a Web page that a browser on a particular operating system can't support. The browser will then attempt to replace the requested color with an approximation composed of two or more other colors it can produce. The result may or may not be acceptable to the graphic designer. It may also appear somewhat grainy since it's composed of different pixel intensities rather than a single intensity over the colored space.

Docking station - a hardware frame and set of electrical connection interfaces that enable a notebook computer to effectively serve as a desktop computer. The interfaces typically allow the notebook to communicate with a local printer, larger storage or backup drives, and possibly other devices that are not usually taken along with a notebook computer. A docking station can also include a network interface card (NIC) that attaches the notebook to a local area network (LAN).

Domain name locates an organization or other entity on the Internet. For example, the domain name : www.totalbaseball.com locates an Internet address for "totalbaseball.com" at Internet point 199.0.0.2 and a particular host server named "www". The "com" part of the domain name reflects the purpose of the organization or entity (in this example, "commercial") and is called the top-level domain name.

Downloading is the transmission of a file from one computer system to another, usually smaller computer system. From the Internet user's point-of-view, to download a file is to request it from another computer (or from a Web page on another computer) and to receive it. Uploading is transmission in the other direction: from one, usually smaller computer to another computer.

Driver - a program that interacts with a particular device or special (frequently optional) kind of software. The driver contains the special knowledge of the device or special software interface that programs using the driver do not. In personal computers, a driver is often packaged as a dynamic link library (DLL) file.

DSL (Digital Subscriber Line) is a technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines.

DVD (digital versatile disc) is an optical disc technology that is expected to rapidly replace the CD-ROM disc (as well as the audio compact disc) over the next few years. The digital versatile disc (DVD) holds 4.7 gigabyte of information on one of its two sides, or enough for a 133-minute movie. With two layers on each of its two sides, it will hold up to 17 gigabytes of video, audio, or other information. (Compare this to the current CD-ROM disc of the same physical size, holding 600 megabyte.

Dynamic HTML is a collective term for a combination of new Hypertext Markup Language (HTML) tags and options, that will let you create Web pages more animated and more responsive to user interaction than previous versions of HTML. Much of dynamic HTML is specified in HTML 4.0. Simple examples of dynamic HTML pages would include (1) having the color of a text heading change when a user passes a mouse over it or (2) allowing a user to "drag and drop" an image to another place on a Web page. Dynamic HTML can allow Web documents to look and act like desktop applications or multimedia productions.

E-business (electronic business), derived from such terms as "e-mail" and "e-commerce," is the conduct of business on the Internet, not only buying and selling but also servicing customers and collaborating with business partners. One of the first to use the term was IBM, when, in October, 1997, it launched a thematic campaign built around the term. Today, major corporations are rethinking their businesses in terms of the Internet and its new culture and capabilities.

E-mail virus - computer code sent to you as an e-mail note attachment which, if activated, will cause some unexpected and usually harmful effect, such as destroying certain files on your hard disk and causing the attachment to be remailed to everyone in your address book.

E-signature (digital signature) (not to be confused with a digital certificate)-a electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document, and possibly to ensure that the original content of the message or document that has been sent is unchanged. Digital signatures are easily transportable, cannot be imitated by someone else, and can be automatically time-stamped.

Electromagnetic field - sometimes referred to as an EM field, is generated when charged particles, such as electrons, are accelerated. All electrically charged particles are surrounded by electric fields. Charged particles in motion produce magnetic fields. When the velocity of a charged particle changes, an EM field is produced. Electromagnetic fields were first discovered in the 19th century, when physicists noticed that electric arcs (sparks) could be reproduced at a distance, with no connecting wires in between. This led scientists to believe that it was possible to communicate over long distances without wires. The first radio transmitters made use of electric arcs. These "spark transmitters" and the associated receivers were as exciting to people in the early 20th century as the Internet is today. This was the beginning of what we now call wireless communication.

Now here's something useful - Emoticon - On the Internet in e-mail, chatting, and posted messages, an emoticon (sometimes referred to as a "smiley") is a short sequence of keyboard letters and symbols, usually emulating a facial expression, expressing a feeling that supplements the message. One of our contributors says that to read these you can either tilt your head or turn the monitor on its side.
:-) Smile
;-) Smile with a wink
:-( Sad
:-D Big grin
:-o Wow! or I'm surprised
:-P Sticking out your tongue
:- User happens to be Popeye
=:O Frightened (hair standing on end)
%*@:-( Hung over
(_8-(|) Homer Simpson
C|:-= Charlie Chaplin
=|:-)= Abe Lincoln
*<:-) Santa Claus
-:-) User sports a mohawk and admires Mr. T

Encoder - a program that converts an audio WAV file into an MP3 file, a highly-compressed sound file that preserves the quality of a CD recording. (The program that gets the sound selection from a CD and stores it as a WAV file on a hard drive is called a ripper.) An MP3 encoder compresses the WAV file so that it is about one-twelfth the size of the original digital sound file. The quality is maintained by an algorithm that optimizes for audio perception, losing data that will not contribute to perception.

Encryption is the conversion of data into a form, called a ciphertext, that cannot be easily understood by unauthorized people. Decryption is the process of converting encrypted data back into its original form, so it can be understood. The use of encryption/decryption is as old as the art of communication. (Technically, a code is a means of representing a signal without the intent of keeping it secret; examples are Morse code and ASCII.) Simple ciphers include the substitution of letters for numbers, the rotation of letters in the alphabet, and the "scrambling" of voice signals by inverting the sideband frequencies. More complex ciphers work according to sophisticated computer algorithms that rearrange the data bits in digital signals. In order to easily recover the contents of an encrypted signal, the correct decryption key is required. The key is an algorithm that "undoes" the work of the encryption algorithm. Alternatively, a computer can be used in an attempt to "break" the cipher.

In computers, the term environment when unqualified usually refers to the combination of hardware and software in a computer. In this usage, the term platform is a synonym. We often tend to think of environment as short for operating system environment, but, with the exception of UNIX-based operating systems, the operating system usually implies an underlying hardware microprocessor that the operating system is designed to run on.

Ethernet is the most widely-installed local area network (LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol. Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second). 10-Gigabit Ethernet provides up to 10 billion bits per second.

Extension - an optional addition to the file name in a suffix of the form ".xxx" where "xxx" represents a limited number of alphanumeric characters depending on the operating system. (In Windows 3.1, for example, a file name extension or suffix can have no more than three characters, but in Windows 95 and later, it can have more.) The file name extension allows a file's format to be described as part of its name so that users can quickly understand the type of file it is without having to "open" or try to use it. The file name extension also helps an application program recognize whether a file is a type that it can work with.
2) In programming, an extension is a file containing programming that serves to extend the capabilities of or data available to a more basic program. Extensions are sometimes required to be stored in a separate extensions file so that they're easy to locate. When installing software, you may be instructed to take one or more steps related to installing extensions (or these steps may automatically be done for you).

Export - to convert a file into another format than the one it is currently in. Once the file is exported to the desired format (specified in its file name suffix), it can be opened and worked on by an application that recognizes and uses this format. Adobe Photoshop and other programs use this term. Other applications such as Word let you export a file by simply specifying the appropriate file name suffix when you use the "Save as" selection. A file that has not been exported to a desired file format can be imported by an application program and then opened and used.

Execute - to run the program in the computer, and, by implication, to start it to run. In usage, people run programs and systems execute them. That is, a system user asks the system to run the program (or sets it up so that this happens automatically at a certain time) and, as a result, the system executes the program. Typically, we don't say that a program is executing; we say that it is running. An executable is a file that contains a program - that is, a particular kind of file that is capable of being executed or run as a program in the computer. In a Disk Operating System or Windows operating system, an executable file usually has a file name extension of .bat, .com, or .exe.

GIF (the original and preferred pronunciation is DJIF; it stands for Graphics Interchange Format) is one of the two most common file formats for graphic images on the World Wide Web. The other is the JPEG. On the Web and elsewhere on the Internet (for example, bulletin board services), the GIF has become a de facto standard form of image.

JPEG (usually pronounced JAY-pehg) is also a term for any graphic image file produced by using a JPEG standard. A JPEG file is created by choosing from a range of compression qualities (actually, from one of a suite of compression algorithms). When you create a JPEG or convert an image from another format to a JPEG, you are asked to specify the quality of image you want. Since the highest quality results in the largest file, you can make a trade-off between image quality and file size.

Source code and object code refer to the "before" and "after" versions of a computer program that is compiled (see compiler) before it is ready to run in a computer. The source code consists of the programming statements that are created by a programmer with a text editor or a visual programming tool and then saved in a file. For example, a programmer using the C language types in a desired sequence of C language statements using a text editor and then saves them as a named file. This file is said to contain the source code. It is now ready to be compiled with a C compiler and the resulting output, the compiled file, is often referred to as object code. The object code file contains a sequence of instructions that the processor can understand but that is difficult for a human to read or modify. For this reason and because even debugged programs often need some later enhancement, the source code is the most permanent form of the program.