One of the most basic concepts, and a fundamental unit of analysis within psychology is the self.
Humans have very well developed self-concepts.
Humans possess self-awareness, the ability to introspect and to see oneself as an individual separate from other individuals.
People possess self-concern: They desire to keep themselves alive.
A derivation of the principle of self-concern is the principle of self-enhancement: people try to view themselves positively, and frequently see themselves more positively than is warranted.
A derivation of the principle of self-enhancement is the principle of self-association: People perceive things that are associated with the self positively.