According to Freud, Id is the part of the mind that is composed of biological impulses that contains our basic psychic energy, or libido, and is expressed through stress reduction. Thus we act in an attempt to reduce this tension to a more tolerable level. To meet the needs and maintain a comfortable level of tension, it is necessary to interact with the real world. For example, hungry people should go in search of food if they want to release hunger-induced tension. Therefore, it is necessary to establish some sort of proper link between the demands of id and reality.