HTML5 spec can be overwhelming for web developers trying to understand how to use HTML5 in their sites and web apps. Much of the spec is written for browser makers and other implementers, not web developers, and contains highly technical and very esoteric language.
Rejoice, because to eliminate the confusing nature of the spec, the WHATWG, one of the two groups that oversees the creation of HTML has released a version of the HTML5 spec written specifically for web developers.
The web developer version of HTML5 strips out all the elements that are only of interest to browser makers, and focuses on developers, making for a more readable, understandable document. Also the new website hosting the web developer version has a much cleaner, simpler design.
HTML 5 Spec for Web Developers Released
under Web Designing