Anatta, "non-self", is the Buddhist teaching that there is no permanent, unchanging self or soul underlying a person. What is conventionally called a "self" is, on analysis, a bundle of five ever-changing aggregates (skandhas): material form, feeling, perception, mental formations and consciousness. None of these is permanent, none is wholly in one's control, and none, singly or together, is a fixed essence one could point to as the real "I."
The teaching has a canonical setting. In what the tradition counts as the Buddha's second discourse, the Discourse on the Characteristic of Non-self, he examines each aggregate in turn and shows that what is impermanent and bound up with suffering cannot rightly be taken as "mine, I, or my self." Non-self stands with impermanence (anicca) and unsatisfactoriness (dukkha) as one of the three marks of all conditioned existence. It is the doctrine that divides Buddhism most sharply from the Hindu traditions, whose atman it directly denies, the point on which the two great Indian streams part.