In general, semantics is the study of meaning. (The word
"semantic" comes from the Greek semantikos, or "significant
meaning," derived from sema, or "sign.") Semantic Web
technologies help separate meanings from data, document content,
or application code, using technologies based on open standards.
If a computer understands the semantics of a document, it
doesn't just interpret the series of characters that make up
that document: it understands the document's meaning. The
Semantic Web provides a common framework that allows data to be
shared and reused across application, enterprise, and community
boundaries. You can think of the Semantic Web as an efficient
way to represent data on the World Wide Web, or as a database
that is globally linked, in a manner understandable by machines,
to the content of documents on the Web. Semantic technologies
represent meaning using ontologies and provide reasoning through
the relationships, rules, logic, and conditions represented in
those ontologies. To represent the Sema