Semantic Web and Resource Description Framework
Need defined
HTML can only say that the span of text "ID586172" is something that should be positioned near "Acme Gizmo" and "$199", etc. There is no way to say "this is a catalog" or even to establish that "Acme Gizmo" is a kind of title or that "$199" is a price. There is also no way to express that these pieces of information are bound together in describing a discrete item, distinct from other items perhaps listed on the page.
Semantic Web
The semantic web comprises the standards and tools of XML, XML Schema, RDF, RDF Schema and OWL that are organized in the Semantic Web Stack. The OWL Web Ontology Language Overview describes the function and relationship of each of these components of the semantic web:


Dries Buytaert welcomed us by saying he was a little nervous facing the 3000 people at DrupalCon SF this year. He got started by showing a web site