HTML 5 is the next revision of the Hypertext Markup Language (HTML), the standard programming language for describing the contents and appearance of Web pages. HTML 5 was adopted by the new HTML working group of the World Wide Web Consortium (W3C) in 2007. This group published the first public draft of HTML 5 in January 2008, but refinements are expected to continue for several years before HTML 5 becomes a formal recommendation.

In theory, HTML 5 will allow the Web browser to become a development platform. A primary goal for HTML 5 is to ensure interoperability among browsers so that Web applications and documents behave the same way no matter which HTML 5-compliant browser is used to access them. (Older browsers that do not support HTML 5 will be able to ignore the new constructs and still produce legible Web page s.)