Contingency is a central concept in metaphysics used to describe events, entities, or states of affairs that are neither impossible nor necessary. Something contingent exists or occurs under certain conditions, but there is no requirement that it had to exist or happen in exactly that way. Philosophical discussions of contingency often connect with possibility, necessity, causation, free will, determinism, existence, and identity, especially when considering whether aspects of reality are fixed or could have unfolded differently.