HTML 
Hypertext Markup Language 
HTML is a collection of formatting commands that you can add to a document so that it can be displayed on the Web. The HTML commands embedded in the page format the page's text and graphic elements. The last version of HTML was version 4.01. Development and maintenance of HTML standards is coordinated by the World Wide Web Consortium (W3C). In 2000, the W3C replaced HTML 4.01 with the new XHTML, which could be thought of as version 5.0 of HTML. XHTML fully supports the commands and features of HTML 4.01, but it's actually an application written in a language called XML (Extensible Markup Language). Unlike with HTML, developers can "extend" the standard by creating new types of markup without having to wait for the W3C to officially release a new version.