The main difference between Hypertext Markup Language (HTML) and Extensible Markup Language (XML) is that HTML is a markup language used to create web pages and XML is also a language markup but is primarily used for sharing information primarily for those connected to the Internet. HTML was created by Tim Berners-Lee as a way for him and several colleagues to share research information (Wikipedia, 2006). Early versions of HTML were based on loose syntax rules. HTML code written according to these earlier rules would not be considered valid by today's standards. HTML was first released as a language in 1993. The HTML standards have been continually modified and updated over the years since its inception. Version 4.0 was released in 1997 by the World Wide Web Consortium (W3C), and the current version is 4.01, released in 1999 (Wikipedia, 2006). Since the release of version 4.0 in 1997, the W3C has focused on the development of XHTML which is an XML equivalent of HTML. HTML used several different entity types such as attributes, character references, data types, and attributes to format a web page. Web pages are created using elements called tags. Tags are predefined by HTML and tags are used to define how a web page will be presented in a browser and control elements such as background color, font size, type and color. Tags are also used to insert links into a web page allowing the user to visit specified pages on different websites or different pages within the same website. Tags also allow a designer to include various multimedia presentations such as photos, music and video files. Annotations are grouped into smaller categories called structural, presentational, and hypertext (Wikipedia, 2006). Structural tags define the physical layout of a page, where different data should be displayed along with other structural parameters such as the use of a header tag such as "H6" which defines the size of the text between the H6 and H6 end tags. Presentation tags define the appearance of text, for example certain words being bolded or italicized. Under Publishing Rules 4.0, most presentation markup tags have been deprecated (Wikipedia, 2006) and the use of cascading style sheets is recommended. Hypertext tags use anchor tags and are used to direct visitors to a different location within the same page or site and are also used to direct visitors to pages on other sites..