Jean Piaget is a renowned psychologist known for his theories on human development. His pioneering work in developmental psychology emphasized the stages through which children progress as they learn and interact with their environment. Piaget proposed that cognitive development occurs in four stages: sensorimotor, preoperational, concrete operational, and formal operational. His insights into how children think and learn revolutionized education and psychology, highlighting the importance of active engagement in the learning process. Piaget's legacy continues to influence contemporary understanding of child development and education, shaping teaching methods and psychological research worldwide.