Philosophy has almost as many definitions as there have been philosophers, both as a subject matter and an activity, and no simple definition can do it justice. The issue of the definition of philosophy is thus a controversial subject that is nowadays tackled by Metaphilosophy (or the philosophy of philosophy). The word is derived from the ancient Greek words philo-, to love or to befriend, and -sophia, wisdom.
Modern usage of the term is much broader; the concept of philosophy encompasses all of knowledge and all that can be known, including the means by which such knowledge can be acquired. However, in the contemporary English-speaking academic world, the term is often used implicitly to refer to analytic philosophy and, in non-English speaking countries, it often refers implicitly to a different, European strain, continental philosophy. The ancient Greeks organized the subject into five basic categories: metaphysics, epistemology, ethics, politics and aesthetics. This organization of the subject is still largely in use in Western philosophy today.
Thought or thinking is a mental process which allows beings to model the world, and so to deal with it effectively according to their goals, plans, ends and desires. Words referring to similar concepts and processes in the English language include cognition, sentience, consciousness, idea, and imagination. Thinking involves the cerebral manipulation of information, as when we form concepts, engage in problem solving, reason and make decisions. Thinking is a higher cognitive function and the analysis of thinking processes is part of cognitive psychology.