This document summarizes key concepts in human development from several theorists. It outlines Piaget's stages of cognitive development from sensorimotor to formal operations. It also describes Kohlberg's six stages of moral development and Erikson's psychosocial stages from infancy to late adulthood. The document then discusses physical, cognitive, and psychosocial issues at different developmental periods before concluding that addressing problems or delays in development can help clients develop more effective coping strategies as adults.