GLOSSARY

ASCII

Acronym for the American Standard Code for Information Interchange. Pronounced ask-ee, ASCII is a code for representing English characters as numbers, with each letter assigned a number from 0 to 127. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.

 

ASCII File

A text file in which each byte represents one character according to the ASCII code. Contrast with a binary file, in which there is no one-to-one mapping between bytes and characters. Files that have been formatted with a word processor must be stored and transmitted as binary files to preserve the formatting. ASCII files are sometimes called plain text files.

 

Binary File

A file stored in binary format. A binary file is computer-readable but not human-readable. All executable programs are stored in binary files, as are most numeric data files.

 

Bit-depth

The number of distinct colors that can be represented by a piece of hardware or software. Color depth is sometimes referred to as bit depth because it is directly related to the number of bits used for each pixel. A 24-bit video adapter, for example, has a color depth of 2 to the 24th power (about 16.7 million) colors. One would say that its color depth is 24 bits.

 

Client/Server Architecture

A network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers ). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.

 

Compression Algorithm

An encoding formula that reduces the size of a digital file while still preserving its essential information. The GIF, JPEG, and MPEG file formats all rely on compressions algorithms.

 

Directory

A special kind of file used to organize other files into a hierarchical structure. Graphical user interfaces may use the term folder instead of directory.

 

DNS

Short for Domain Name System (or Service), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4.

 

Domain

A group of computers and devices on a network that are administered as a unit with common rules and procedures. Within the Internet, domains are defined by the IP address. All devices sharing a common part of the IP address are said to be in the same domain.

 

Domain Name

A name that identifies one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. Every domain name has a suffix that indicates which top-level domain (TLD) it belongs to. There are only a limited number of top-level domains, including .com, .org, .net. .edu, .gov, country domains, and others.

 

FTP

Abbreviation of File Transfer Protocol, the protocol used on the Internet for sending files.

 

FTP Client

An application that runs on a personal computer or workstation and makes it easy for you to upload and download files to and from a server.

 

GIF

Pronounced jiff or giff (hard g) stands for Graphics Interchange Format, a bit-mapped graphics file format used by the World Wide Web. The GIF format relies on a "lossless" compression algorithm to compress digital files.

 

GUI

Pronounced goo-ee, acronym for graphical user interface. A program interface that takes advantage of the computer's graphics capabilities to make the program easier to use. Popular GUIs, such as the ones used by Apple Macintosh and Microsoft Windows, include pointers and a mouse, icons, a desktop, windows, and menus to help the user manipulate files easily.

 

HTML

Short for HyperText Markup Language, the authoring language used to create documents on the World Wide Web. HTML is similar to SGML, although it is not a strict subset.

 

HTML 4.0 Standard

The current set of standards designed to regulate the use and structure of HTML, as developed by the World Wide Web Consortium (W3C). Browsers vary in the degree to which they support the standard.

 

HTTP

Short for HyperText Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.

 

Internet

A global network connecting millions of computers. Unlike online services, which are centrally controlled, the Internet is decentralized by design. Each Internet computer, called a host, is independent. Its operators can choose which Internet services to use and which local services to make available to the global Internet community. Remarkably, this anarchy by design works exceedingly well.

 

InterNIC

A collaborative project between AT&T and Network Solutions, Inc. (NSI) supported by the National Science Foundation. Offers a variety of services to Internet Users, particularly domain name and IP address assignment.

 

IP Address

An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address.

 

ISO

Short for International Organization for Standardization. Note that ISO is not an acronym; instead, the name derives from the greek word iso, which means equal. Founded in 1946, ISO is an international organization composed of national standards bodies from over 75 countries. For example, ANSI (American National Standards Institute) is a member of ISO. ISO has defined a number of important computer standards, the most significant of which is perhaps OSI (Open Systems Interconnection), a standardized architecture for designing networks.

 

ISP

Short for Internet Service Provider, a company that provides access to the Internet. For a monthly fee, the service provider gives you a software package, username, password and access phone number. Equipped with a modem, you can then log on to the Internet and browse the World Wide Web and USENET, and send and receive e-mail. Many ISPs also offer Web hosting.

 

JPEG

Short for Joint Photographic Experts Group, and pronounced jay-peg. JPEG uses a "lossy" compression algorithm to reduce the size of color image files. Although it can reduce file sizes to about 5% of their uncompressedl size, some detail is lost in the compression.

 

Linux

A freely-distributable, open source implementation of UNIX that runs on a number of hardware platforms, including Intel and Motorola microprocessors. It was developed mainly by Linus Torvalds. Because it's free, and because it runs on many platforms, including PCs, Macintoshes and Amigas, Linux has become extremely popular in the last few years.

 

Lossless Compression

Refers to data compression techniques in which no data is lost. The PKZIP compression technology is an example of lossless compression. For most types of data, lossless compression techniques can reduce the amount of disk space a file needs by only about 50%. For greater compression, one must use a lossy compression technique. Note, however, that only certain types of data -- graphics, audio, and video -- can tolerate lossy compression. You must use a lossless compression technique when compressing data and programs.

 

Lossy Compression

Refers to data compression techniques in which some amount of data is lost. Lossy compression technologies attempt to eliminate redundant or unnecessary information. Most video compression technologies, such as MPEG, use a lossy technique.

 

MIME

Short for Multipurpose Internet Mail Extensions, a specification for formatting non-ASCII messages so that they can be sent over the Internet. Many e-mail clients now support MIME, which enables them to send and receive graphics, audio, and video files via the Internet mail system. In addition, MIME supports messages in character sets other than ASCII. There are many predefined MIME types, such as GIF graphics files and PostScript files. It is also possible to define your own MIME types.

 

Pixel

Short for Picture Element, a pixel is a single point in a graphic image. Graphics monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. On color monitors, each pixel is actually composed of three dots -- a red, a blue, and a green one. Ideally, the three dots should all converge at the same point, but all monitors have some convergence error that can make color pixels appear fuzzy.

 

Protocol

An agreed-upon format for transmitting data between two devices. The protocol determines the following:

• the type of error checking to be used
• data compression method, if any
• how the sending device will indicate that it has finished sending a message
• how the receiving device will indicate that it has received a message

From a user's point of view, the only interesting thing about protocols is that your computer or device must support the right ones if you want to communicate with other computers.

 

Resolution

Refers to the sharpness and clarity of an image. The term is most often used to describe monitors, printers, and bit-mapped graphic images. In the case of dot-matrix and laser printers, the resolution indicates the number of dots per inch. For graphics monitors, the screen resolution signifies the number of dots (pixels) on the entire screen. For example, a 640-by-480 pixel screen is capable of displaying 640 distinct dots on each of 480 lines, or about 300,000 pixels.

 

SGML

Abbreviation of Standard Generalized Markup Language, a system for organizing and tagging elements of a document. SGML was developed and standardized by the International Organization for Standardization (ISO) in 1986. SGML itself does not specify any particular formatting; rather, it specifies the rules for tagging elements. These tags can then be interpreted to format elements in different ways.

 

Tag

A command inserted in a document that specifies how the document, or a portion of the document, should be formatted. Tags are used by all format specifications that store documents as text files, including SGML and HTML.

 

TCP/IP

Abbreviation for Transmission Control Protocol/Internet Protocol, the suite of communications protocols used to connect hosts on the Internet. TCP/IP uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks.

 

Telnet

A terminal emulation program for TCP/IP networks such as the Internet. The Telnet program runs on your computer and connects your PC to a server on the network. You can then enter commands through the Telnet program and they will be executed as if you were entering them directly on the server console. This enables you to control the server and communicate with other servers on the network.

 

UNIX

Pronounced yoo-niks, a popular multi-user, multitasking operating system developed at Bell Labs in the early 1970s. UNIX was one of the first operating systems to be written in a high-level programming language (C). Due to its portability, flexibility, and power, UNIX has become the leading operating system for workstations, and is one of the most common operating systems used by Web servers.

 

URL

Abbreviation of Uniform Resource Locator, the global address of documents and other resources on the World Wide Web. The first part of the address (e.g., "http") indicates what protocol to use, and the second part specifies the IP address or the domain name where the resource is located.

 

TCP/IP

Abbreviation for Transmission Control Protocol/Internet Protocol, the suite of communications protocols used to connect hosts on the Internet. TCP/IP uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks.

 

W3C

Short for World Wide Web Consortium, an international consortium of companies involved with the Internet and the Web. The W3C was founded in 1994 by Tim Berners-Lee, the original architect of the World Wide Web. The organization's purpose is to develop open standards so that the Web evolves in a single direction rather than being splintered among competing factions. The W3C is the chief standards body for HTTP and HTML.

 

Web Portal

A Web site or service that offers a broad array of resources and services, such as e-mail, forums, search engines, and on-line shopping malls. The first Web portals were online services, such as AOL, that provided access to the Web, but by now most of the traditional search engines have transformed themselves into Web portals to attract and keep a larger audience.

 

Web Server

A computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. Any computer can be turned into a Web server by installing server software and connecting the machine to the Internet. There are many Web server software applications, including public domain software from NCSA and Apache, and commercial packages from Microsoft, Netscape and others.

 

World Wide Web

A system of Internet servers that support specially formatted documents. The documents are formatted in HTML, which supports links to other documents, as well as graphics, audio, and video files. Not all Internet servers are part of the World Wide Web.

 

WYSIWYG

Pronounced wizzy-wig, stands for "what you see is what you get." A WYSIWYG application is one that enables you to see on the display screen exactly what will appear when the document is printed or, in the case of Web pages, viewed in a browser. Popular WYSIWYGs for building Web pages are Macromedia Dreamweaver and Adobe GoLive.

 

XHTML

Extensible Hypertext Markup Language is a hybrid between HTML and XML specifically designed for Net device displays. XHTML is a markup language written in XML; therefore, it is an XML application.

 

XML

Short for Extensible Markup Language, a specification developed by the W3C. XML is a pared-down version of SGML, designed especially for Web documents. It allows designers to create their own customized tags, enabling the definition, transmission, validation, and interpretation of data between applications and between organizations. Whether XML eventually supplants HTML as the standard Web formatting specification depends a lot on whether it is supported by future Web browsers.