OWL, or the Web Ontology Language, is a semantic web language designed to represent rich and complex knowledge about things, groups of things, and relations between them. It allows users to create ontologies, which are formal representations of a set of concepts within a domain and the relationships between those concepts. OWL is built on top of RDF (Resource Description Framework) and is used to enable interoperability between systems. There are three sublanguages of OWL: OWL Lite, OWL DL, and OWL Full, each offering different levels of expressiveness and complexity. OWL is widely used in various fields, including bioinformatics, knowledge management, and artificial intelligence, to facilitate data sharing and integration across diverse applications.