The W3C and its members have long sought the ability to mix extractable structured content with existing publishing processes to improve the machine-processability of the Web. Microformats have been a successful step in this direction, but the models embraced by the domain-specific formats are not global or interoperable. The rich layers of the Semantic Web initiative have not easily been integrated until now allowing documents to indicate metadata that can be expressed in the Resource Description Framework (RDF) model.
Publishers now have a low-effort semantic markup capability that client tools will begin to harvest as a natural part of the browsing process. No longer will “where on the Web” and “when” be the only extracted information from browsing sessions, but also “who authored the pages” and “where are they about” and “what content can be reused based on the license”. The RDFa initiative grew out of the Creative Commons efforts to express license metadata about published content but grew to support a wider set of use cases. For more information, see the RDFa specification or the RDFa Primer which has also been updated.