HTML5 is being developed as the next major revision of HTML (HyperText Markup Language), the core markup language of the World Wide Web.
HTML5 is the proposed next standard for HTML 4.01 and XHTML 1.0. It aims to reduce the need for proprietary plug-in-based rich internet application (RIA) technologies such as Adobe Flash, Microsoft Silverlight, Apache Pivot, and Sun JavaFX.
The First Public Working Draft of HTML5 was completed in 2008 and will reach W3C Recommendation by late 2010.
Although the final specification is not to reach W3C Candidate Recommendation till 2012, many parts of the specification are stable and may be implemented in browsers.
So is it time to start developing websites and applications in HTML5?
Yes and no. Yes, you can start developing using the features already supported by the major browsers. No, you should not use HTML5 experimental features on any client projects where you must have an absolute 100% accessibility compliance.
In my next post I will talk about the major features in HTML5 and CSS3 that you can use now, and have vendor support across all major browsers.