MangoLog

Resource Description Framework (RDF) is a family of specifications for a metadata model that is often implemented as an application of XML. The RDF family of specifications is maintained by the World Wide Web Consortium (W3C).

The RDF metadata model is based upon the idea of making statements about resources in the form of a subject-predicate-object expression, called a triple in RDF terminology. The subject is the resource, the "thing" being described. The predicate is a trait or aspect about that resource, and often expresses a relationship between the subject and the object. The object is the object of the relationship or value of that trait.

This mechanism for describing resources is a major component in what is proposed by the W3C's Semantic Web activity: an evolutionary stage of the World Wide Web in which automated software can store, exchange, and utilize metadata about the vast resources of the Web, in turn enabling users to deal with those resources with greater efficiency and certainty. RDF's simple data model and ability to model disparate, abstract concepts has also led to its increasing use in knowledge management applications unrelated to Semantic Web activity.

OWL is an acronym for Web Ontology Language, a markup language for publishing and sharing data using ontologies on the Internet. OWL is a vocabulary extension of the Resource Description Framework (RDF) and is derived from the DAML+OIL Web Ontology Language. Together with RDF and other components, these tools make up the Semantic Web project.

The OWL specification is maintained by the World Wide Web Consortium (W3C).

OWL currently has three flavors: OWL Lite, OWL DL, and OWL Full. These flavors incorporate different features, and in general it is easier to reason about OWL Lite than OWL DL and OWL DL than OWL Full. OWL Lite and OWL DL are constructed in such a way that every statement can be decided in finite time; OWL Full can contain endless 'loops'.