In psychoanalytic theory, the most primitive, unconscious element of human personality.
Sigmund Freud believed that human personality consisted of three components: the id, the ego, and the superego. The id is the part of the personality that includes such basic biological impulses or drives as eating, drinking, eliminating wastes, avoiding pain, attaining sexual pleasure, and aggression. The id operates on the "pleasure principle," seeking to satisfy these basic urges immediately with no regard to consequences. Only when tempered through interaction with the ego (reality) and superego (conscience) does the id conform to what is considered socially acceptable behavior.
According to Freud, anxiety is caused by the conflict between the id's powerful impulses and the modifying forces of the ego and superego. The more id-driven impulses are stifled through physical reality or societal norms, the greater the level of anxiety. People express their anxiety in various ways, including nervousness, displaced aggression, and serious anxiety disorders. Healthy personalities are those that have learned to balance the id, ego and superego forces.
Atkinson, Rita L.; Richard C. Atkinson; Edward E. Smith; and Ernest R. Hilgard. Introduction to Psychology. 9th ed. San Diego: Harcourt Brace Jovanovich, 1987.
Zimbardo, Philip G. Psychology and Life. 12th ed. Glenview, IL: Scott, Foresman, 1988.