The Semantic Web is an evolving extension of the World Wide Web in which the semantics of information and services on the web is defined, making it possible for the web to understand and satisfy the requests of people and machines to use the web content.[1][2] It derives from W3C director Tim Berners-Lee's vision of the Web as a universal medium for data, information, and knowledge exchange
http://en.wikipedia.org/wiki/Semantic_Web