Sigmund Freud proposed that the personality consists of three different elements: the Id, the Ego and the Superego.

The Id is an aspect of personality that is driven by internal and basic drives and needs. These are typically instinctual, such as hunger, thirst, and the drive for sex, or libido. The Id is impulsive and often unaware of the implications of actions. It is unconscious, selfish, childish and present from birth.

The Superego works in contradiction to the id and it comprises the organized part of the personality structure. It is partly unconscious, and can be thought of as a type of conscience that punishes misbehavior with feelings of guilt, controlling our sense of right and wrong.

The ego acts according to the reality principle and holds psychic functions such as judgment, tolerance, reality testing, control, planning, defense, synthesis of information, intellectual functioning, and memory, which help us to make sense of our thoughts and the world around us. It also acts as a moderator between the id and superego. When a conflict arises between the two, the ego employs defense mechanisms.

Psychosexual development is a central element of Freud’s psychoanalytic theory, stating that human beings, from birth, possess an instinctual libido (sexual energy) that develops in five stages: the oral, the anal, the phallic, the latent, and the genital.