The new HTML 5 standard is gaining significant traction even though HTML 5 is still in the draft process and has not yet been ratified by W3C. Browser makers are already implementing key features of HTML 5 and bringing robust support for some of its most advanced capabilities to end users.
HTML 5 has many new features. HTML 5 specification is the description of a vocabulary that you can write to define a web page. HTML 5 can be written using two different syntaxe: html and XML. What is the syntax best for you depends on your developer needs, markets and applications. An HTML5 (text/html) browser will be flexible in handling incorrect syntax, while the XHTML variant of HTML 5 (XHTML5) will need correct markup to work.