The first stage of psychosexual development is the oral stage, spanning from birth until the age of two years, where in the infant’s mouth is the focus of libidinal gratification derived from the pleasure of feeding at the mother’s breast, and from the oral exploration of his or her environment, i. e. the tendency to place objects in the mouth. The id dominates, because neither the ego nor the super ego is yet fully developed, and, since the infant has no personality (identity), every action is based upon the pleasure principle.
Nonetheless, the infantile ego is forming during the oral stage; two factors contribute to its formation: (i) in developing a body image, he or she is discrete from the external world, e. g. the child understands pain when it is applied to his or her body, thus identifying the physical boundaries between body and environment; (ii) experiencing delayed gratification leads to understanding that specific behaviors satisfy some needs, e. g. crying gratifies certain needs.  Anal stage
The second stage of psychosexual development is the anal stage, spanning from the age of eighteen months to three years, wherein the infant’s erogenous zone changes from the mouth (the upper digestive tract) to the anus (the lower digestive tract), while the ego formation continues. Toilet training is the child’s key anal-stage experience, occurring at about the age of two years, and results in conflict between the Id (demanding immediate gratification) and the Ego (demanding delayed gratification) in eliminating bodily wastes, and handling related activities (e.
g. manipulating excrement, coping with parental demands). The style of parenting influences the resolution of the Id–Ego conflict, which can be either gradual and psychologically uneventful, or which can be sudden andpsychologically traumatic. The ideal resolution of the Id–Ego conflict is in the child’s adjusting to moderate parental demands that teach the value and importance of physical cleanliness and environmental order, thus producing a self-controlled adult.
Yet, if the parents make immoderate demands of the child, by over-emphasizing toilet training, it might lead to the development of a compulsive personality, a person too concerned with neatness and order. If the child obeys the Id, and the parents yield, he or she might develop a self-indulgent personality characterized by personal slovenliness and environmental disorder. If the parents respond to that, the child must comply, but might develop a weak sense of Self, because it was the parents’ will, and not the child’s ego, who controlled the toilet training.
Phallic stage The third stage of psychosexual development is the phallic stage, spanning the ages of three to six years, wherein the child’s genitalia are his or her primary erogenous zone. It is in this third infantile development stage that children become aware of their bodies, the bodies of other children, and the bodies of their parents; they gratify physical curiosity by undressing and exploring each other and their genitals, and so learn the physical (sexual) differences between “male” and “female” and the gender differences between “boy” and “girl”.
In the phallic stage, Latency stage[ The fourth stage of psychosexual development is the latency stage that spans from the age of six years until puberty, wherein the child consolidates the character habits he or she developed in the three, earlier stages of psychologic and sexual development. Whether or not the child has successfully resolved the Oedipal conflict, the instinctual drives of the id are inaccessible to the Ego, because his or her defense mechanisms repressed them during the phallic stage.
Hence, because said drives are latent (hidden) and gratification is delayed — unlike during the preceding oral, anal, and phallic stages — the child must derive the pleasure of gratification from secondary process-thinking that directs the libidinal drives towards external activities, such as schooling, friendships, hobbies, etc. Anyneuroses established during the fourth, latent stage, of psychosexual development might derive from the inadequate resolution either of the Oedipus conflict or of the Ego’s failure to direct his or her energies towards socially acceptable activities.
Genital stage The fifth stage of psychosexual development is the genital stage that spans puberty and adult life, and thus occupies most of the life of a man and of a woman; its purpose is the psychologic detachment and independence from the parents. The genital stage affords the person the ability to confront and resolve his or her remaining psychosexual childhood conflicts.
As in the phallic stage, the genital stage is centered upon the genitalia, but the sexuality is consensual and adult, rather than solitary and infantile. The psychological difference between the phallic and genital stages is that the ego is established in the latter; the person’s concern shifts from primary-drive gratification (instinct) to applying secondary process-thinking to gratify desire symbolically and intellectually by means of friendships, a love relationship, family and adult responsibilities.