For Freud, the mind is best conceptualized in two distinct components, the conscious and unconscious. The unconscious portion contains the thoughts we may potentially have, as well as the desires which dictate our behavior without our awareness. Zizek refers to this region as storing the "unknown-knowns" - the things we don't know that we know. Societal regulations force us to repress certain aspects of ourselves, and the unconscious serves as the storehouse for this collection. Many of our inner urges are too disturbing for the conscious mind (and society at large) to cope with immediately. Therefore, we sublimate these secrets into a region we cannot face directly.
The ego is responsible for repressing unconscious thoughts. Things that are too disturbing to face immediately are pushed out of awareness by the ego. However, the unconscious continues to exert influence on the behavior of the individual. This psychological pressure creates a continuous battle between the ego and unconscious portions of the psyche. The dynamics of this struggle are the target of much of Freud's psychoanalytic theories. He described the mind as composed of various components. Each component is responsible for one of the various functions the mind executes. The relations of these parts are the subject of much debate in psychoanalysis.