HTML 5 is basically the next version of HTML (HyperText Markup Language), the programming language for website presentation and rendering.
The World Wide Web consortium (W3C) has long managed the development of HTML. However, their focus moved to the more strict, non-backwards compatible XHTML as a ‘fix’ for the web. Committing to XHTML created a lot of work for browsers with limited advancement. This created some resistence from web and browser developers.
Formation of WHATWG
In 2003, Opera and Mozilla proposed to the W3C that they move past XHTML and look at real world use of HTML and rich web applications. After the W3C did not respond positively, Opera, Mozilla and Apple formed WHATWG, the Web Hypertext Application Technology Working Group. The mission of the WHATWG is to return to more open standards by advancing HTML. WHATWG wants to modernize HTML to the point where proprietary plug in technologies are not required to deliver real world web applications. They started working on a new HTML specification in July 2004 which they branded Web Application 1.0. These specifications were accepted by the W3C as the basis for HTML5.
The W3C dropped XHTML in 2007 and created the HTMLWG (HTML Working Group) in response to the WHATWG. Working under the WHATWG umbrella, Ian Hickson of Google Inc authored the HTML5 draft specification recommendation for the W3C which was published in January 2008. The current version of that draft can be found here (last updated August 12, 2010).
HTML5 continues to move through the process of becoming a formal W3C Recommendation.
What does HTML5 Add?
HTML5 tries to simplify the web by becoming more of an open standard, by making definitive rules for managing elements, and by eliminating the need for proprietary plugins. While adding new features and elements, HTML5 also purges some elements deemed unnecessary based on the goals of the WHATWG and HTMLWG. We won't see the old applet,
The HTML5 feature that seems to inspire the greatest interest is probably the easy incorporation of video into HTML code without the use of external plugins like Adobe Flash, Apple Quicktime or Microsoft Silverlight. The manipulation of graphics and audio also garner lots of attention. There are many new elements and attributes designed to make HTML5 more open while advancing the web application user experience. Consider a few of the new elements and features:
Video element - As you might imagine, this element defines how a video is embedded into an HTML5 page. The video element includes control attributes for user interaction with playback. Codecs will have to be defined as well.
Device element - This element adds to the potential of HTML5. You can assign page access to a physical device, such as a web cam. The device element was not in the original HTML5 specification draft.
Geolocation API - With the advent of such geographic location applications such as FourSquare and Gowalla, a geolocation API with HTML5 adds another realm of potential uses, especially for mobile web applications. Locations would be identified by their unique cross-sections of latitude and longitude.
Offline Web applications - With HTML5, developers can identify what pages should be cached locally using a manifest document called manifest.cache. With a local cache, applications can load information faster and of course, still access certain content when disconnected from the server.
What about Flash, Java, Silverlight, Quicktime Plugins?
Does HTML5 represent the end of Flash and Silverlight plugins? Not necessarily. Plugins may still be able to incorporate different controls for video and graphics presentation yet unavailable in HTML5 going forward. There may still be opportunities for innovation at the plugin level; however, much of what we use plugins for will move into HTML itself.
HTML5 should simplify web development, and is supported by major browsers (even Internet Explorer 9 as declared by Microsoft at Mix 2010 in Las Vegas, NV) although to varying extents. HTML5 could and should be the longterm future of web markup.