From The Art and Popular Culture Encyclopedia
In philosophy, ontology (from the Greek: of being and science, study, theory) is the study of being or existence and forms the basic subject matter of metaphysics. It seeks to describe or posit the basic categories and relationships of being or existence to define entities and types of entities within its framework.
Ontology can be said to study conceptions of reality; and, for the sake of distinction, at least to the extent to which its counterpart, epistemology can be represented as being a search for answers to the questions "What do you know?" and "How do you know it?", ontology can be represented as a search for an answer to the question "What are the knowable things?".
Some philosophers, notably of the Platonic school, contend that all nouns refer to entities. Other philosophers contend that some nouns do not name entities but provide a kind of shorthand way of referring to a collection (of either objects or events). In this latter view, mind, instead of referring to an entity, refers to a collection of mental events experienced by a person; society refers to a collection of persons with some shared interactions, and geometry refers to a collection of a specific kind of intellectual activity.
Any ontology must give an account of which words refer to entities, which do not, why, and what categories result. When one applies this process to nouns such as electrons, energy, contract, happiness, time, truth, causality, and God, ontology becomes fundamental to many branches of philosophy.
- Philosophy of science