According to Sigmund Freud, a psychoanalyst, there are five stages of psychosexual development. The five stages are oral, anal, phallic, latency, and genital. In each stage, different areas of the child's body become the focus of their pleasure and their main source of sexual arousal. Within each stage there are conflicts between the rules of society and the sex drive. A correct resolution of each of the conflicts will move the child from that particular stage to the next. Failing to correctly resolve these problems will cause the child to become fixated in that stage, thus causing many personality and behavioral disorders later in life. .
The first stage in Freud's theory is the oral stage with begins at birth and continues until around two years old. The focus of this stage is the mouth and gratification through nursing/eating, sucking, gumming, swallowing, and biting. To the child, the mother's breast is a source of food and also represents her love. In this stage, the child is controlled by the id, which is all about desire, and they want instant gratification for anything. If there is forceful or inadequate feeding, the child could possibly remain fixated in this stage. Some adult results of this stage can include nail biting, overeating, smoking, gum/pencil/pen chewing, drinking, sarcasm (biting personality), and verbal hostility. For a child to successfully complete this stage and move onto the anal stage, they must receive instant gratification when they want it.
The second stage is the anal stage which lasts from age two to age 4. The anus is the main area of focus in the stage and it involves bowel movements and controlling those movements. During this stage a child will learn to become "potty trained". At the beginning of this stage a child may think of the movements as pleasurable or displeasurable. During the toilet training they will learn how to control such movements.