A Priori is a Latin term used in philosophy to refer to knowledge that is independent of experience, observation, or other empirical evidence. A proposition that is known a priori can be considered to be true independently of any specific instance or situation. The term is often contrasted with its opposite, a posteriori, which describes knowledge that is based on observation, experience, or evidence. The distinction between a priori and a posteriori knowledge is an important concept in epistemology, the branch of philosophy concerned with knowledge and belief.