An accurate comparison for Freud's personality theory is to say that the personality of a human is like an iceberg. Just as the greater percentage of an iceberg is beneath the water, our personalities exist mostly below our level of awareness. Freud placed an important emphasis on this level of unconscious awareness, believing it to be the area in which most important personality processes occur as well as the area consisting of an individual's instincts and psychic energy. He called this submerged part of the brain the "id", the unconscious mind, which has no contact with reality.
Freud believe that the id was one of three structures that make up what personality is, the other two being the ego and the superego. The ego emerges from the personality as children realize the demands and constraints of actual reality. What sets the ego apart from the id is the concept of reasoning in order to make decisions. However, the ego of a personality is without morality. This is where the third structure, the superego, comes into play. The superego is the "moral branch of personality." This is the area which distinguishes right from wrong, better known as the conscious mind.
According to Freud, the conflicting demands of the id, ego and superego create anxiety, "when the ego blocks the pleasurable pursuits of the id". He also holds the relationship between the id, ego and superego responsible for repression (much repression from early childhood experiences). Repression, a natural defense mechanism for humans, is created from the personality-created anxiety. Repression happens when irrational id impulses are pushed back into the unconscious mind and out of awareness.