Sigmund Freud's psychosexual stages are a series of five developmental phases that he proposed as essential for personality development. These stages are oral, anal, phallic, latency, and genital. Freud believed that each stage is characterized by the focus of pleasure on different areas of the body, and that unresolved conflicts during any stage could lead to personality issues in adulthood. During the oral stage, which occurs from birth to about 18 months, infants derive pleasure from oral activities like sucking. The anal stage follows, from 18 months to 3 years, where the focus shifts to controlling bladder and bowel movements. The phallic stage, from ages 3 to 6, involves the exploration of gender identity and relationships. The latency stage, from 6 years to puberty, is a period of social development, while the genital stage, beginning in puberty, focuses on mature sexual relationships.