OWL 2 is a semantic web language designed to represent rich and complex knowledge about things, groups of things, and relations between them. It builds on the original OWL (Web Ontology Language) and provides more expressive features, allowing for better reasoning about the data. With OWL 2, users can create ontologies that define classes, properties, and relationships in a structured way. This enables machines to understand and process information more effectively, facilitating tasks like data integration, sharing, and retrieval across different systems and applications.