HTML5

HTML5 is the next generation of HTML. It is a revision of the Hypertext Markup Language, a set of markup tags used in creating web pages. HTML5 was adopted by the World Wide Web Consortium (W3C) in 2007, who published the draft in January 2008.

HTML5 offers several features over its predecessor HTML4 which includes

• New parsing rules for enhanced flexibility
• New attributes
• Elimination of outmoded and redundant attributes
• Immediate-mode drawing
• Drag and drop
• Back button management
• Timed media playback
• Offline editing
• Messaging enhancements
• Detailed rules for parsing
• Multipurpose Internet Mail Extensions (MIME) and protocol handler extensions
• Improved canvass support
  

HTML5 is designed that older browsers that do not support the new version can ignore its new constructs without affecting the presentation of the web page.

For more information on HTML5 visit http://en.wikipedia.org/wiki/HTML5
Reference http://whatis.techtarget.com