Its XML counterpart is XHTML 1.1, successor of XHTML 1.0 defined in 2000 and revised in 2002 by the W3C.

The newest XHTML 2.0 was at first meant to replace both, but the fact that it was not compatible with XHTML 1.1 raised quite a controversy.

This, added to the fact that some major internet companies and non-profit organizations wanted to expand the typical browser experience to include other internet usages like messaging and media playback led to the creation of the Web Hypertext Application Technology Working Group (WHATWG), that released in 2005 the first version of the HTML 5 specification.

The W3C started in 2007 a new HTML working group that took the WHATWG HTML 5 specification as a basis, leading to the publication of the first HTML 5 draft in 2008.

The W3C HTML 5 working group is led by Ian Hickson from Google, Inc (WHATWG HTML 5 specification editor, CSS 2.1 co-editor, Acid2 and Acid3 developer) and David Hyatt from Apple, Inc (Safari/Webkit project leader, Firefox co-founder).

The HTML 5 specification defines both HTML and XHTML document types.

The W3C maintains a list of differences between HTML 5 and HTML 4.

I will try to explain these differences in separate posts:

• <section> and associated new block-level elements,
• <audio> & <video> elements,
• offline web applications,
• … TBC …