According to Sigmund Freud, the key to a healthy personality is a balance between the Id, the Ego and the Superego.
The Id, the Ego and the Superego are three theoretical constructs, in terms of whose activity and interactions, the mental life can be described and complex human behaviours formed. Hence, these three components of the personality structure are functions of the mind rather than parts of the brain.
The Id
According to Freud, the Id is the only component of the personality structure that is present from birth. This facet of personality is entirely unconscious and includes all the instinctive and primitive behaviours, hence allowing us to get our basic needs met as newborns.
Freud believed that the Id is ruled by the pleasure principle. This driving force seeks immediate gratification of all needs, wants and urges.
In other words, the Id wants whatever feels good at the time, with no reality of the situation.
For example, if a child is hungry s/he will cry until the demands of the Id are met.
And so, if these needs are not satisfied at once, the result is a state of anxiety or tension. In the above example, the child will cry louder!
The Ego
Even if the Id is very important for newborns, to immediately satisfy some of the Id’s needs and desires in the long run, is not always possible. That is why within the next three years, as a child starts to interact more with his/her environment, the second part of the personality begins to develop.
The Ego is based on the reality principle. The Ego understands that other people have needs and desires and that sometimes being impulsive or selfish can eventually hurt us. Therefore, the Ego strives to achieve the Id’s desires in both realistic and socially appropriate ways.
The reality principle weighs the costs and benefits of an action before deciding to act upon or abandon impulses. In many cases, the Id's impulses can be satisfied
References: http://psychology.about.com/od/theoriesofpersonality/a/personalityelem.htm http://allpsych.com/psychology101/ego.html http://wilderdom.com/personality/L8-4StructureMindIdEgoSuperego.html