Sigmund Freud proposed that the mind is divided into three parts: the id, ego, and superego. The id operates on the pleasure principle, seeking instant gratification. The ego mediates between the id and reality. The superego incorporates social norms and ideals from our parents. Freud also described psychosexual stages of development from infancy through adulthood, where the id's libido or sexual energy focuses on different erogenous zones, such as the mouth, anus, genitals, and finally mature genital sexuality in adulthood.