The story of HTML5 in a nutshell
HTML5 was born as a completion and beginning of the Web 2.0, but do we all know about its emergence? At the times of HTML4 and XHTML 1.1 the W3C made a new group for defining a new standard, XHTML 2.0, which had no backward compatibility with other HTML or XHTML previous versions and that was much more strict than previous versions. Some people thought that this new standard wouldn't fulfill web developers' needs of simplicity and flexibility and for these reasons Ian Hickson announced the foundation of a new research group about HTML in 4 June 2004, research group that later in the years would have given birth to the modern HTML5: the WHAT group. Because both the XHTML2 and WHAT groups coexisted inside the W3C, web developers, browsers makers etc. were pretty confused, so that many people started to be worried about the future of HTML, as you can read in this historic post by Edd Dumbill: The future of HTML. It's for these reasons that Tim Berners Lee, the HTML creator decided not to confirm the XHTML2 group for next years, having the idea to renew HTML4 adjusting it to best fulfill web's need, much fuller of media such as audio, videos etc. That's how HTML5 had birth: inside the WHAT group, following certain "right" guidelines in the XHTML2 and releasing itself from the tie to SGML and XML, but being well structured and defined at the same time! All this story was in a nutshell, but you relly dig into details that would really show how complex this birth is being, as it's still in progress! P.S. Just remember HTML5 is not a standard yet but a recommendation (somes says HTML5 will be a standard only in 2020!!!)