Freud describes the human mind as interaction of id, ego, super-ego. The the ego and his own pdf represents a constant in the personality as it is always present.
The id is governed by the ‘pleasure principle’. Early in the development of his theory Freud saw sexual energy as the only source of energy for the id. Freud felt it necessary to add another instinct to the id. So, he proposed thanatos, the death instinct. Obviously, the rest of the personality would have somehow to deal with these two instincts. His idea of id had wide influence.
It is the dark, inaccessible part of our personality It is filled with energy reaching it from the instincts, but it has no organisation, produces no collective will, but only a striving to bring about the satisfaction of the instinctual needs subject to the observance of the pleasure principle”. The ego is the surface of the personality, the part you usually show the world. The ego is governed by the ‘reality principle’, or a practical approach to the world. Conscious awareness resides in the ego, although not all of the operations of the ego are conscious. The ego separates out what is real.