mattur - 10:16 pm on Mar 31, 2013 (gmt 0)
(Split off from other thread to focus on web standards)
... [HTML5] is still officially a Candidate Recommendation, with some elements at risk of being dropped "due to lack of implementation" which apparently means "We've been selling it for ten years but nobody's buying".
The W3C HTML5.0 Spec is a bit irrelevant to implementors and web developers now. It's a dated snapshot, and its target audience is the patent lawyers who work for W3C Members like Google, Microsoft, Intel, Apple, Netflix, IBM etc. Loads of bugs in the spec have been fixed since then, and new functionality has been added, so it's already well out of date.
The W3C HTML Working Group* is currently working on a new snapshot called HTML5.1 [w3.org]. This snapshot will also become out of date as the Living Spec (or in W3C parlance Nightly version) moves on. These numbered snapshots are for patent lawyers, not web developers.
Web developers should always refer to the latest version of the HTML Spec which is maintained here, under an open licence that allows copying and reproduction:
The W3C version is basically the same, apart from a few bike-sheddy differences, and a more restrictive licence. The W3C Nightly HTML spec and the WHATWG HTML Living Spec are kept broadly in sync so you can use either.
Website authors, designers and developers will probably find this a (far) better reference to use:
See also A Word About CSS4 [xanthir.com]
*I'm sort-of a member of the HTMLWG