RDF for Describing Resources
RDF is a general-purpose metadata framework
Uniform syntax (XML), structure (RDF) and semantics (community defined) significantly improves interoperability and utility of web resources and description
Common structure (data model) provides interoperability of separate packages of metadata defined by different resource description communities
Common structure and transfer allows for integration of both first and trusted third party metadata
More information http://www.w3.org/RDF