Ontology Concept

In computer science and information science, an ontology is a formal representation of a set of concepts within a domain and the relationships between those concepts. It is used to reason about the properties of that domain, and may be used to define the domain.

An ontology provides a similar role for the semantic Web or the semantic government as does a schema, say, for relational databases.

(Note: the term ontology is also used in philosophy, where it refers to the nature of being. That broader sense is not applicable here.)