OWL is a language for processing web information.
Ontology is about the exact description of things and their relationships.
For the web, ontology is about the exact description of web information and relationships between web information.
OWL is a part of the "Semantic Web Vision" - a future where:
OWL was designed to provide a common way to process the content of web information (instead of displaying it).
OWL was designed to be read by computer applications (instead of humans).
OWL and RDF are much of the same thing, but OWL is a stronger language with greater machine interpretability than RDF.
OWL comes with a larger vocabulary and stronger syntax than RDF.
OWL has three sublanguages:
By using XML, OWL information can easily be exchanged between different types of computers using different types of operating system and application languages.
OWL became a W3C (World Wide Web Consortium) Recommendation in February 2004.
A W3C Recommendation is understood by the industry and the web community as a web standard. A W3C Recommendation is a stable specification developed by a W3C Working Group and reviewed by the W3C Membership.