<p>Just like it reads.</p>

From wikipedia:
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. It
  derives from World Wide Web Consortium
  director Sir Tim Berners-Lee's vision
  of the Web as a universal medium for
  data, information, and knowledge
  exchange.