HTML5 is a new version of HTML and XHTML. The HTML5 draft specification defines a single language that can be written in HTML and XML. It attempts to solve issues found in previous iterations of HTML and addresses the needs of Web Applications, an area previously not adequately covered by HTML.
Some links to check out:
• HTML5 differences from HTML4
• WHATWG and HTML5 FAQ
• HTML5 validator
• HTML5 specification tracker
resource: HTML5.org
