Freud

Structure of The Personality 

Freud's iconic work on the subject of abnormality was recognised as pioneering, particularly his model of the human personality. He suggested that the human psyche is constructed of three interacting elements;

The id:

The reservoir of unconscious and instinctual psychic energy that we are born with. The most integral aspect being the psychic energy's libido, or life instincts, however this energy may also direct itself into aggression. 

The id operates upon basic principles of pleasure, constantly attempting to gratify the these instincts through pleasurable activity. 

The Ego: 

Represents our conscious self and develops during early childhood, regulating interactions with our immediate environment. The ego is also responsible for trying to balance the demands of the id for self-gratification with the moral rules imposed by the superego of conscience. 

The ego operates upon the reality principle, in that it constantly balances the demands of the real world against the instinctive drives of the id.

The Superego:

The personal moral authority, or conscience, developing later in childhood through identification with one or other parent. At this point, the child internalises the moral rules and social norms of society. 

References:

Green, S. McGinley, R. Willerton, J. Wilson, J. Bailey, J. (2008) AQA AS Psychology. Cheltenham. Nelson Thornes.