In computer science and information science, an ontology is a formal naming and definition of the types, properties, and interrelationships of the entities that really or fundamentally exist for a particular domain of discourse. It is thus a practical application of philosophical ontology, with a taxonomy. An ontology compartmentalizes the variables needed for some set of computations and establishes the relationships between them. (Source: Wikipedia.org) PoolParty offers several ways to use ontologies: You can use online available ontologies, that are already provided with the default setup. You can import custom ontologies and also link to online sources.