Metaphysics is the branch of philosophy concerned with explaining the nature of reality, being, and the world. Its name derives from the Greek words μετά (metá) (meaning "after") and φυσικά (physiká) (meaning "those on nature"), "those on nature" referring to those works on nature by Aristotle in antiquity^. Metaphysics addresses questions such as:

• What is the nature of reality?
• What is humankind's place in the universe?
• Are colors objective or subjective?
• Does the world exist outside the mind?
• What is the nature of objects, events, places?

A central branch of metaphysics is ontology, the investigation into what types of things there are in the world and what relations these things bear to one another. The metaphysician also attempts to clarify the notions by which people understand the world, including existence, objecthood, property, space, time, causality, and possibility.

More recently, the term "metaphysics" has also been used more loosely to refer to "subjects that are beyond the physical world".

Before the development of modern science, scientific questions were addressed as a part of metaphysics known as "natural philosophy"; the term "science" itself meant "knowledge". The Scientific Revolution, however, made natural philosophy an empirical and experimental activity unlike the rest of philosophy, and by the end of the eighteenth century it had begun to be called "science" in order to distinguish it from philosophy. Metaphysics therefore became the philosophical enquiry into subjects beyond the physical world. Natural philosophy and science may still be considered topics of metaphysics, if the definition of "metaphysics" includes empirical explanations.