A fundamental study within philosophy, which is concerned with the state of being. Ontology is a branch of metaphysics, and answers the question of what entities can be said to exist, and the relationships between these entities. [from Greek ὄν = on, and ὄντος, ontos = being; that which is, and -logia (λογία) = logical discourse]. Leibniz (1646 – 1716) used the term in the 17th century.

Ontology deals with essential dichotomies, such as:

universals and particulars

substance and accident

abstract and concrete objects

essence and existence

determinism and indeterminism

monism and dualism

idealism and materialism