Developmental psychology offers several major theoretical frameworks to explain how individuals grow and develop into healthy adults. These include Sigmund Freud's psychosexual theory, which focuses on stages related to bodily erogenous zones; Erik Erikson's psychosocial theory, which builds on Freud's work but emphasizes the role of social interactions in shaping identity; Jean Piaget's cognitive theory, which describes the stages of children's thinking and reasoning; and Lawrence Kohlberg's theory of moral development, which posits that moral thinking evolves through levels that are dependent on cognitive development.