Ontology (from Greek ontos "being" + logos "study") is the branch of philosophy that studies the nature of being, existence, and reality.

On the path of knowledge, ontology is relevant because:

• The central question is "What is existence?"

• The path provides an ontological analysis of experience, experiencer, and their relationship

• It questions what is ultimately real versus what is illusory

• It examines categories of being such as objects, individuals, and worlds

The ontological position of the path of knowledge is nondual - there is only one existence appearing as the diversity of experience. The criteria for truth (that which changes is false) is used to determine what is ultimately real.

See also epistemology.