The five stages of Freud's theory of psychosexual development included the oral, anal, phallic, latency, and genital stages. During childhood, the oral phase of development begins, the mouth being the source of all pleasant interactions. The baby derives pleasure from rewarding activities such as sucking and eating. Freud believed that if the child's needs were not met during this period, problems with dependency, aggression and oral fixations would occur. During adulthood, oral fixations can generate negative habits such as eating, smoking and nail biting. During the anal stage of development, toddlers and preschoolers must learn to control their bodily needs, the development of control leads to independence and a sense of accomplishment. Improper resolution of this crisis can lead to obsessiveness and orderliness if a parent is too harsh during toilet training and disorderly and destructive personalities if a parent is too relaxed. During the phallic phase, libido is concentrated on the genitals. During this stage of development, children begin to discover the differences between boys and girls and begin to struggle with sexual desires towards the parent of the opposite sex. During the latency period, libido is suspended and children and adolescents focus on repressing sexual desires. At this time children focus on hobbies and friends. During the final stage of psychosexual development, the genital stage, people develop strong sexual interests in the opposite sex to satisfy instinct