Glossary of Terms
= Index DOT Html/Css by Brian Wilson =

Index DOT Html: Main Index | Element Tree | Element Index | HTML Support History
Index DOT Css: Main Index | Property Index | CSS Support History | Browser History

ASCII Acronym for 'American Standard Code for Information Interchange.' ASCII is the dominant character set encoding used by present-day computers (this may slowly change.) Current ASCII uses 7 bits of data for each character, allowing for 128 distinct character code points.

BNF Acronym for Backus-Naur Form. This was originally a syntax used to define the ALGOL programming language in the late 1950s/early 60s. First created by John Backus and refined a year later by Peter Naur. It soon became the de-facto presentation method of conveying the formal syntax of a programming language, and many programmatic syntax analysis tools (such as LEX and YACC) also use variations of this syntax.

Browser Also known as a web client or User Agent. A World Wide Web access program that can request documents or other files from a web server, and render/execute them on a user's display device.

CALS Acronym for Continuous Acquisition and Life-Cycle Support (formerly known as Computer-aided Acquisition and Logistics Support.) CALS is a Department of Defense (DoD) strategy for achieving effective creation, exchange, and use of digital data for weapon systems and equipment. Parts of the HTML table model were modeled after the CALS table implementation. More information can be found from the US Navy CALS home page at

CDATA Abbreviation for Character Data. CDATA is a data type model used in SGML and XML with DTDs. According to HTML 4.0,
"CDATA is a sequence of characters from the document character set and may include character entities. User agents should interpret attribute values as follows:
  • Replace character entities with characters
  • Ignore line feeds
  • Replace each carriage return or tab with a single space.
  • User agents may ignore leading and trailing white space in CDATA attribute values"
The documentation for HTML 4 also places many additional constraints on various attribute's values which are often not expressable using DTD syntax or data types. On this site, the constrained set of values are described.

Note: In HTML 4+ and XHTML, the "document character set" is Unicode. In HTML 2.0, 3.0 and 3.2, it is ISO-8859-1.

CERN Acronym for 'Conseil Européen pour la Recherche Nucléaire.' This is a research center for high energy physics in Geneva, Switzerland - It is also the birthplace of the World Wide Web. See also

CGI Acronym for 'Common Gateway Interface'. This is the specification governing how Web browsers can communicate with and request services from Web servers. CGI also includes the format and syntax for passing information from browsers to servers via forms or document-based queries in HTML.

Dither Color dithering simulates a color value that can't be displayed using a mixture of displayable colors, eg: gray can be created by mixing black and white values. This allows non-displayable colors to be implied to the eye - it is tricked into blending the color mixture into the intended color. The ratios and pattern of the color mix, along with the resolution of the display device are factors determining the quality of the dithering effect.

DTD Acronym for Document Type Definition. This is a formal SGML specification for a document. A DTD defines the structural elements and combinatorial rules that can be used to create instances of documents. The HyperText Markup Language is defined using one of these formal definitions.

ECMA Acronym for European Computer Manufacturer's Association - a standards body. One standard they have created is EcmaScript (the standards-version of JavaScript.)

Formed in March 1996 by the W3C and composed of experts from W3C member companies, it was created to develop HTML standards.

FTP Acronym for File Transfer Protocol. A TCP/IP-based protocol used on the Internet to copy files to and from FTP servers elsewhere on a network.

Gopher A program/protocol developed at the University of Minnesota which provides for a menu-driven presentation of a variety of Internet services, including WAIS, Telnet, and FTP.

HTML Acronym for HyperText Markup Language. HTML is defined using SGML and is the markup language used on the World Wide Web. Its most distinguishing feature is the ability to create hypertext links (hyperlinks) for joining disparate documents and files together.

HTTP Acronym for HyperText Transfer Protocol. The protocol used to communicate between Web clients and servers. HTTP can convey the MIME type of the transferred file(s), and many other identifying attributes along with the file itself.

More commonly referred to as its shorthand form: Hyperlink. A hyperlink is defined by HTML markup that creates an element that can be activated by the user to change the user's focus from one document (or part of a document) to another.

ICADD Acronym for "International Committee for Accessible Document Design." This group developed the ICADD DTD markup language for use in converting SGML documents to a format that is easier to handle by non-visual rendering devices. See Spyglass' "Description of the ICADD mechanism" document for more details. [Now links to's last known snapshot due to Link Rot.]

IETF Acronym for Internet Engineering Task Force. The IETF is the protocol engineering and development arm of the Internet consisting of a large, open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. The IETF was the main oversight body for HTML during much of the HTML 2.0 era timeframe. It is open to any interested individual. See also

Internet A worldwide collection of networks that began with technology and equipment funded by the US Department of Defense in the 1970s (called ARPAnet) that today links users in nearly every known country, speaking nearly every known language.

An Internet Draft is released by an arm of the Internet Engineering Task Force (IETF.) Internet Drafts exist only as discussion documents with no formal status. They are valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. An Internet Draft is often released before a Request For Comments.

ISO Acronym for International Standards Organization. This is the 'granddaddy' of standards organizations worldwide, and is composed of standards bodies from countries all over the world. Most important communications and computing standards are the subject of ISO standards.

MIME Acronym for Multipurpose Internet Mail Extensions. A standard for multi-part, multimedia electronic mail messages and World-Wide Web documents on the Internet. MIME provides the ability to transfer non-textual data, such as graphics, audio and fax.

PERL Acronym for Practical Extraction and Report Language. A powerful, compact programming language that draws from the capabilities of languages like C, Pascal, sed, awk, and BASIC, Perl is emerging as a main language of choice for CGI programs. This is partly due to its portability and the many platforms on which it is currently supported, and also due to its ability to easily manipulate text and ease of use of system services in UNIX.

The Property Value is the specific value(indicated result) of a given Property Name using Cascading Style Sheets. Each Property Name will have its own set of allowable values.

An element that a browser only knows the intrinsic dimensions of. In HTML, 'IMG', 'INPUT', 'TEXTAREA', 'SELECT' and 'OBJECT' elements can be examples of replaced elements - the content of the 'IMG' element will be replaced by the image that the SRC attribute points to.

SDA Acronym for "SGML Document Access" conversion methodologies. SDA attributes were added to HTML 2.0 to aid accessibility for users with visual disabilities. These attributes were dropped from the HTML standards in favor of other, more powerful methods of accessibility-enabling mechanisms. For more information on SDA, see Spyglass' "Description of the ICADD Mechanism" document. (Now linking to's last known good snapshot due to Link Rot.)

Selector An Identifier that binds a style assignment to one or more HTML elements in Cascading Style Sheets. A Selector can represent one or more HTML tags or Style classes.

SGML Acronym for 'Standard Generalized Markup Language'. This is an ISO standard [8879:1986] document definition, specification, and creation mechanism that makes platform and display differences across multiple computers irrelevant to the delivery and rendering of documents.

One or more Style Property Name/Value pairs in Cascading Style Sheets. A Style Property Name is separated from a Property Value by a colon [':'] character.

This is one of over one hundred rendering characteristics used to control layout and appearance of HTML documents in Cascading Style Sheets. Some Names are only applicable to certain element types.

URL Acronym for 'Uniform Resource Locator'. This is the primary addressing scheme used to identify unique Web resources. A URL defines the protocols to be used, the domain name of the Web server where a resource resides, the port address to be used for communication, and the directory path to access a named Web file or resource.

Wide Web
Also known as WWW or W3. This is a term coined by Tim Berners-Lee to describe his original project for CERN. It now refers to the collection of all interconnected Web servers available on the Internet. This group of interconnected documents creates a global 'web' of information.

Wide Web
Also known as the W3C, this is an international industry consortium founded in 1994 to develop common standards for the evolution of the World Wide Web. It was initially established in collaboration with CERN, where the Web originated but is now hosted by other concerns. See also

Note: Much of the content on this page was pulled from existing glossaries on the net and is by no means comprehensive. If you are having any trouble with a particular term that is not all that self-explanatory, you are encouraged to search the vast resources of the net for more information.

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