!-- (HTML comment) | !DOCTYPE | a | abbr | acronym | address | applet | area | b | base | basefont | bdo | big | blockquote | body | br | button | caption | center | cite | code | col | colgroup | dd | del | dfn | dir | div | dl | dt | em | fieldset | font | form | frame | frameset | h1 | h2 | h3 | h4 | h5 | h6 | head | hr | html | i | iframe | img | input | ins | isindex | kbd | label | legend | li | link | map | menu | meta | noframes | noscript | object | ol | optgroup | option | p | param | pre | q | s | samp | script | select | small | span | strike | strong | style | sub | sup | table | tbody | td | textarea | tfoot | th | thead | title | tr | tt | u | ul | var

HTML (HyperText Markup Language) is a non-proprietary format for structuring plain text documents so they can be presented on the Web. A pure HTML document is just a plain text file with an extension of .htm or .html. Typically a web server spits out HTML documents to be viewed by users with web browsers and some sort of connection to the web server. An HTML document presents information with text or objects that can lead to other information via links.

HTML history:

• 1990: HTML (HyperText Markup Language) was specified by Tim Berners-Lee. He also wrote a browser and server for it.
• 1995-11-24: HTML 2.0 published as IETF RFC 1866.
• 1997-01: HTML 3.2 published as a W3C Recommendation. Sadly the math tags were dropped.
• 1997-12: HTML 4.0 published as a W3C Recommendation. Includes three flavors: Strict, Transitional, and Frameset.
• 1999-12: HTML 4.01 published as a W3C Recommendation.
• 2000-01-26: XHTML 1.0 published as a W3C Recommendation. XHTML is a reformulation of HTML as an XML document.
• 2000-05: ISO HTML (based on HTML 4.01 Strict) published as ISO/IEC 15445:2000.
• 2001-05-31: XHTML 1.1 published as a W3C Recommendation.
• 2008-01: HTML 5 and XHTML 5 published as a W3C Working Draft. See HTML5 differences from HTML4 [http://dev.w3.org/html5/html4-differences/].

See the latest version of the HTML specifications at http://www.w3.org. Their material ranges from technically easy to technically difficult.

HTML is a specific implementation of SGML (Standard Generalized Markup Language) for the WWW. XML (eXtensible Markup Language) is a more general implementation of SGML.

An HTML document basically takes plain text and applies special formatting by enclosing portions of it in markup tags (hence the "M" in HTML). The HTML document is also able to point to other files for presentation within the document or for access by clicking on the pointer (hence the "HT" in HTML). EG:

<p>This is text enclosed in paragraph tags.</p>
<p>This text has <b>bold words</b> in it.</p>
<p>This tag presents an image: <img src="hi.gif"></p>
<p>Here is a <a href="Hello.htm">clickable pointer</a>.</p>

HTML tags are also called HTML elements, especially when used the elements are used as objects for CSS or other processes.

A page usually contains 1 document with this basic structure:

<html>
<body>...</body>
</html>

However, a page may contain multiple documents. Hence each frame object is also a window object that contains 1 document object.

<html>
</html>