The Semantic Web is a use of the WWW for a web of data.
The SemanticWebCerealBox analogy may help you understand it.
There is a lot of debate about what the term "Semantic Web" means.
Some of the major definitions:
- little-s semantic web
- The developing web of data and protocols, presently growing on the Internet.
The Semantic Web is characterized by the use of Graphs and NetworkedData.
- SemanticWebUseCases - what the semantic web can do for us
- SeedApplications - initial steps to the future
- Wikipedia's "Semantic Web" entry - a more technical look at what the Semantic Web is all about.
- EmbeddingRDFinHTML - how to make it easy for computers to find RDF connected to web pages
- The W3C Semantic Web Activity - scary looking documents
- RepresentingVCardinRDFOWL - current work on an updated OWL ontology for vCard (RFC6350)