Introduction to HTML (Hyper Text Markup Languages)

HTML stands for Hyper Text Markup Language. Tim Berners Lee of MIT invented HTML with colleagues from CERN, the European Particle Physics Laboratory, as a means f distributing nonlinear text, called hypertext, to multiple points across the internet. One document links to another through pointers called hyperlinks. Hyperlinks are embedded instructions within one text file that call another file whenever the link is accessed, usually by click of a mouse. The global set of linked documents across the existing Internet framework grew into what is now known as the World Wide Web.
Hypermiedia is an extension of hypertext. It includes images, video, audio, animation and other multimedia data tyates, which can be incorporated into HTML documents. The web can be accuately describd as a hypermedia system.

Hypertext was first conceived by Ted Nelson in 1965. The first widely commercialized hypertext product was HyperCard, conceived by Bill Atkinson and introduced by Apple Computer in 1987. It is incorporated many hypertext and hypermedia concepts, by was a proprietary system that worked only on Macintosh computers.

In contrast, HTML is a cross platform language that works on Windows, Macintosh and UNIX platforms. In additiona HTML and the Web are client/server systems; HyperCard works only on stand-alone Macintosh computers.
A markup language is very different from a programming language. Program files and data files exist separately in traditional applications. In a markup language the instructions and the data reside in the same file. In addition, HTML does not provide data structures or internal logic as do procedural languages such as C or Pascal.

HTML has evolved from other markup languages. IBM created the General Markup Language (GML) in teh late 1960s as a way to move formated documetns across different computer platforms. GML evolved into the Standard Generalized Markup Language in 1986 and was ratified by the International Organization for Standardization (ISO). SGML is a powerful markup language, however it is also very complex and difficult to learn.

HTML is an application SGML. Although it has fewer language elements than SGML, HTML is easier to use and has become the standard method of encoding information for Web documents. AS with GML, HTML facilitates data exchange through a common document form across different types of computer systems and networks on the web.

Whereas SGML is used specifically to define context as opposed to appearance. HTML has evloved into both a contextual and formatting language. By applying a heading style to text using HTML, for example you are not only marking that text contextually as an important topic that begins a new section, you are also applying te visual format element of boldface and a larger font size. HTML files are plain text fiels that have been "marked up" with special language elements called tags, which embedded in the text.

Tags are piece of text, enclosed in angle brackets that provide instructios to program designed to interpret HTML. For example you may want tochange the color of some text in your file. You can do this by embedding opening and closing tags around the text that you wanted colored. If you want an image to appar in your documetn, you can use a tag to specify the source and placement of the image.

HTML interpreters are programs that process the HTML pages and render thamto the user as text pages formatted in accordance with the embedded instructions. Examples of HTML interreters are Netscape Navigator and Microsoft Internet Explorer; these two programs are also called Web browsers.

HTML interpreters are not limited to browsers. Many programs that have come on the market since 1996 include HTML reading and exporting capabilities as built in features. Netscape Communicators for example now allows you to send and receive HTML messages, and you can post fully formatted HTML messages to news and discussion groups. Although HTML was specifically designed fr use on the World Wide Web, many business are finding uses for HTML documents that have little or nothing to do with the Web. HTML fiels ar very small and extremely portable, making htis format an ideal choice when exchanging documents across any type of network.

HTML Standards
The World Wide Web Consortium (W3C) is the standards organization that controls the evolution of HTML. When the W3C fully endorses a technology it publishes a "Recommendation" to the Internet Community. When the W3C evaluates a proposed recommendation, the specifies of the technology are in state of constant flux. Be sure the code you use confirms to the latest recommendation from the W3C.

Generally, do not code to specifications indicated in working drafts, these versions are undergoing discussion and consideration and are generally not yet supported by the major vendors. Recommendations from the W3C become the standards to which vendors pledge full supports. To see W3C Recommendations, you can access the W3C Website at http://w3.org/