The ID:

(i) The Id is the original source of personality, present in the newborn infant, from which the ego and super ego later develop.

(ii) It consists of everything that is inherited, including the instinctual drives—sex and aggression.

(iii) It is closely linked to the biological processes and provides the energy source—the libido for the operation of all three systems.

(iv) It is totally unconscious and works on pleasure principles regardless of any external potential costs of seeking the gratification of impulses.

The Ego:

(i) The ego develops out of Id because of the necessity for dealing with the real world. The ego's task is to hold the Id in check until conditions allows for satisfaction of its impulses.

(ii) It operates on reality principles. For example, a hungry man would want to have food at any cost due to id impulses, but it is the ego which delays this hunger impulse until the appropriate conditions are found.

(iii) The ego is essentially the executive of the personality. It keeps a person working for a living, getting along with people and generally adjusting to the realities of life.

(iv) Ego mediates between the demands of id, the realities of the world and the demands of the super ego.

The Super Ego:

(i) It is related to the values and morals of the society as taught to us by our parents and others. It works according to social norms.

(ii) It is concerned with morality—whether various ways that could satisfy id impulses are right or wrong.

The main functions of the super ego are:

(i) To inhibit the unacceptable impulses of Id such as sex and aggression.

(ii) Freud assumed that Id is energised by two instinctual forces, called life instinct and death instinct. Life instinct is individuals, tendency to construct whereas death instinct is for the distruction. According to Freud, life instinct is more dominant among human beings.

According to Freud, the instinctual life force that energises the Id is called Libido.

It works on the pleasure principle, and seeks immediate gratification. It is source of energy.