Metaphysics is a branch of philosophy that investigates principles of reality transcending those of any particular science. Cosmology and ontology are traditional branches of metaphysics. It is concerned with explaining the fundamental nature of being and the world. Someone who studies metaphysics would be called either a "metaphysician" or a "metaphysicist."

The word derives from the Greek words μετά (metá) (meaning "beyond" or "after") and φυσικά (physiká) (meaning "physical"), "physical" referring to those works on matter by Aristotle in antiquity. The prefix meta- ("beyond") was attached to the chapters in Aristotle's work that physically followed after the chapters on "physics," in posthumously edited collections. Aristotle himself did not call these works Metaphysics. Aristotle called some of the subjects treated there "first philosophy."

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.

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" of epistemological origin. The scientific method, 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. Thereafter, metaphysics became the philosophical enquiry of a non-empirical character into the nature of existence.

Metaphysics has been continuously contended in history as vague or untrue.

Traditionally, it was thought that metaphysics would strive to achieve to reach “behind" the facts, findings and biases appearing to humans, and to tell the ultimate truth about things. In order to metaphysics to be at all possible, the ultimate nature of reality should be, at least in principle, understandable, i.e. the reality should be structured so that it could be identified by logical human thinking. This is the first basic assumption of metaphysics, unproven.

Metaphysics problems are usually composed of several aspects: observations, delusions, and ultimate reality. Here are some examples:

- What is existence? What types of things are there?
- What is the origin of the universe?
- Does reality exist outside the mind?
- If there is a reality, what is its true nature?
- Does free will or action to the laws of nature-dominated world?
- Much explored concepts are also such as the existence and properties of objects, time and space, causality, and the possibility and necessity.

Metaphysics owerlaps with many areas of science. For example, the above question about the universes origin is intensely studied by many of the leading theoretical physicists of the world.

Source: The Finnish Wikipedia