The id is the dark, inaccessible part of our personality, what little we know of it we have learnt from our study of the dream-work and of the construction of neurotic symptoms, and most of this is of a negative character and can be described only as a contrast to the ego. We all approach the id with analogies: we call it a chaos, a cauldron full of seething excitations. It is filled with energy reaching it from the instincts, but it has no organisation, produces no collective will, but only a striving to bring about the satisfaction of the instinctual needs subject to the observance of the pleasure principle. It contains everything that is inherited, that is present at birth, is laid down in the constitution – above all, therefore, the instincts, which originate from the somatic organisation, and which find a first psychical expression here in the id in forms unknown to us. The id comprises the disorganised part of the personality structure that contains the basic drives. The id acts according to the pleasure principle – The pleasure principle states that people seek pleasure and avoid pain, for instance; people seek to satisfy biological and psychological needs – seeking to avoid pain or unpleasant feelings and are aroused by increases in instinctual tension.
The ego is that part of the id which has been modified by the direct influence of the external world. The ego represents what may be called reason and common sense, in contrast to the id, which contains the passions. In its relation to the id it is like a man on horseback, who has to hold in check the superior strength of the horse; with this difference, that the rider tries to do so with his own strength, while the ego uses borrowed forces. The ego comprises that organised part of the personality structure that includes defensive, perceptual, intellectual-cognitive, and executive functions. Conscious awareness resides in the ego, although not all of the operations of the ego are conscious. The ego separates what is real. It helps us to organise our thoughts and make sense of them and the world around us.
The Super-ego can be thought of as a type of conscience that punishes misbehaviour with feelings of guilt. For example: having extra-marital affairs. The Super-ego strives to act in a socially appropriate manner, whereas the id just wants instant self-gratification. The Super-ego controls our sense of right and wrong and guilt. It helps us fit into society by getting us to act in socially acceptable ways. The Super-ego aims for perfection.