OWL

OWL is the W3C standard ontology language designed to represent complex knowledge about hierarchies and relationships between objects.

The Web Ontology Language (OWL) provides a robust computational framework for the Semantic Web. It extends RDF by adding specific vocabulary for describing properties and classes: including relations between classes (e.g. disjointness), cardinality (e.g. exactly one), and characteristics of properties (e.g. symmetry). By utilizing Description Logics, OWL enables automated reasoners like HermiT or Pellet to verify data consistency and infer implicit knowledge without manual tagging. It is the architectural foundation for large-scale knowledge graphs like DBpedia and the Gene Ontology, which manages over 40,000 biological concepts.

https://www.w3.org/TR/owl2-overview/