ID represents the primitive, disorganized, and innate part of the personality, whose function is to reduce tension caused by basic drives or impulses. It operates according to the pleasure principle and disregards the demands of reality. When these impulses conflict with the ego or the superego—the rational and normative part of thought—individuals may experience frustration, constraint, and powerlessness. The absence of these basic instincts, as well as the suppression of individual desires arising from them, can create an inner imbalance, leading to conflicts between what one feels one “should” do and what one wants to do.

The ID is composed of fundamental impulses that Freud referred to as life instincts. Additionally, it contains death instincts, which are associated with destructive and aggressive behaviors.