HTML 5

Filename extension	.html, .htm
Internet media type	text/html
Type code	TEXT
Uniform Type Identifier	public.html
Developed by	World Wide Web Consortium and WHATWG
Type of format	Markup language
Extended from	SGML
Extended to	XHTML5
Open format?	Yes
Website	whatwg.org/html w3.org/TR/html5/

HTML5 is a language for structuring and presenting content for the World Wide Web, a core technology of the Internet. It is the fifth revision of the HTML standard (created in 1990 and standardized as HTML4 as of 1997) and as of September 2011 is still under development. Its core aims have been to improve the language with support for the latest multimedia while keeping it easily readable by humans and consistently understood by computers and devices (web browsers, parsers, etc.). HTML5 is intended to subsume not only HTML4, but XHTML1 and DOM2HTML (particularly JavaScript) as well.
Following its immediate predecessors HTML 4.01 and XHTML 1.1, HTML5 is a response to the observation that the HTML and XHTML in common use on the World Wide Web is a mixture of features introduced by various specifications, along with those introduced by software products such as web browsers, those established by common practice, and the many syntax errors in existing web documents. It is also an attempt to define a single markup language that can be written in either HTML or XHTML syntax. It includes detailed processing models to encourage more interoperable implementations; it extends, improves and rationalises the markup available for documents, and introduces markup and application programming interfaces (API)s for complex web applications.
In particular, HTML5 adds many new syntactical features. These include the <video>, <audio>, <header> and <canvas> elements, as well as the integration of SVG content. These features are designed to make it easy to include and handle multimedia and graphical content on the web without having to resort to proprietary plugins and APIs. Other new elements, such as <section>, <article>, <header>, and <nav>, are designed to enrich the semantic content of documents. New attributes have been introduced for the same purpose, while some elements and attributes have been removed. Some elements, such as <a>, <cite> and <menu> have been changed, redefined or standardized. The APIs and document object model (DOM) are no longer afterthoughts, but are fundamental parts of the HTML5 specification.^[2] HTML5 also defines in some detail the required processing for invalid documents, so that syntax errors will be treated uniformly by all conforming browsers and other user agents.

For More Details Visit: http://en.wikipedia.org/wiki/HTML5