Developmental theories are frameworks that explain how individuals grow and change throughout their lives. These theories focus on various aspects of development, including physical, cognitive, emotional, and social growth. Key figures in this field include Jean Piaget, who studied cognitive development, and Erik Erikson, known for his stages of psychosocial development. These theories help educators, psychologists, and parents understand the typical milestones and challenges individuals face at different ages. By recognizing these patterns, they can better support healthy development and address any potential issues that may arise during the lifespan.