Web Ontology Language (OWL)

The Web Ontology Language (OWL) is a family of knowledge representation languages for authoring ontologies, and is endorsed by the World Wide Web Consortium. This family of languages is based on two (largely, but not entirely, compatible) semantics: OWL DL and OWL Lite semantics are based on Description Logics, which have attractive and well understood computational properties, while OWL Full uses a novel semantic model intended to provide compatibility with RDF Schema.
The W3C-endorsed OWL specification includes the definition of three variants of OWL,
with different levels of expressiveness.
1. OWL Lite was originally intended to support those users primarily needing a classification
hierarchy and simple constraints. Development of OWL Lite tools has thus proven almost
as difficult as development of tools for OWL DL, and OWL Lite is not widely used.
2. OWL DL was designed to provide the maximum expressiveness possible while retaining
computational completeness, decidability, and the availability of practical reasoning
algorithms. OWL DL includes all OWL language constructs, but they can be used only under
certain restrictions.
3. OWL Full is based on a different semantics from OWL Lite or OWL DL, and was designed
to preserve some compatibility with RDF Schema.