The Semantic Web is an evolving extension of the World Wide Web in which the semanticsof 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 W3C director Tim Berners-Lee's vision of the Web as a universal medium for data, information, and knowledge exchange.
At its core, the semantic web comprises a set of design principles,collaborative working groups,
and a variety of enabling technologies. Some elements of the semantic
web are expressed as prospective future possibilities that are yet to
be implemented or realized. Other elements of the semantic web are expressed in formal specifications. Some of these include Resource Description Framework (RDF), a variety of data interchange formats (e.g. RDF/XML, N3, Turtle, N-Triples), and notations such as RDF Schema (RDFS) and the Web Ontology Language (OWL), all of which are intended to provide a formal description of concepts, terms, and relationships within a given knowledge domain.
With the semantic web, the following video clip is a scary thought - It's possible