Ontology Web Language
The Ontology Web Language (OWL) is a set of markup languages which are designed for use by applications that need to process the content of information instead of just presenting information to humans. OWL ontologies describe the hierarchical organization of ideas in a domain, in a way that can be parsed and understood by software. OWL has more facilities for expressing meaning and semantics than XML, RDF, and RDF-S, and thus OWL goes beyond these languages in its ability to represent machine interpretable content on the Web. OWL is part of the W3C recommendations related to the Semantic Web.