Html Vs. Xml

The main difference between Hyper text markup language (HTML) and Extensible markup language (XML) is that HTML is a markup language used for creating web pages and XML is also a markup language but is primarily used for information sharing mainly those connected to the internet.

HTML was created by Tim Berners-Lee as a way for he and several colleagues to share research information (Wikipedia, 2006). The earliest versions of HTML were based on loose syntax rules. HTML code written using these earlier rules would not be considered valid using today's standards. HTML was first published as a language in 1993. The Standards for HTML have been continually changed and updated over the years since its creation. Version 4.0, was published in 1997 by the World Wide Web Consortium (W3C), and the current version is 4.01, published in 1999 (Wikipedia, 2006). Since the publishing of 4.0 in 1997 the W3C has been focused on the development of XHTML which is an XML based equivalent to HTML.

HTML used several different types of entities 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 such things 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 web sites or different pages within the same website. Tags also allow a designer to include various media presentations such as photos, music and video files.

Markups are grouped in smaller categories know as structural, presentational and hypertext(Wikipedia, 2006). Structural markups define the physical layout of a page, where the various pieces of data are to be displayed and other structural settings such as using a header tag like "H6" which defines the size of text between the H6 and H6 end tags. Presentational markups define how text will look such as some words being bold or italicized text. Under 4.0 publication rules most presentational markup tags have been depreciated (Wikipedia, 2006) and the use of cascading style sheets is recommended. Hypertext markups 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. HTML 4.0 also defines several character entities which allow the designer to display characters on a web page that are normally recognized by HTML as markup characters. For example each HTML tag is encased by the less than and greater than characters (). If a designer wished to display the less than character on a web page a character entity would be used which tells HTML to display the character rather than seeing it as a markup character.

XML is based on the Standard Generalized Markup Language (SGML) and is not intended as a replacement to HTML. The one major difference between HTML and XML is the use of tags. HTML requires the use of predetermined tags and XML permits usage of user defined tags. XML was a published W3C recommendation as of February 1998 (Wikipedia, 2006).

XML provides a text based means to apply a tree-based structure to