Jean Piaget's Theory is a cognitive development theory that explains how children learn and think as they grow. Piaget proposed that children progress through four stages: sensorimotor, preoperational, concrete operational, and formal operational. Each stage represents a different way of understanding the world, with children building knowledge through experiences and interactions. In the sensorimotor stage, infants learn through their senses and actions. The preoperational stage involves symbolic thinking but lacks logical reasoning. The concrete operational stage allows for logical thinking about concrete events, while the formal operational stage enables abstract reasoning and problem-solving. Piaget's work has significantly influenced education and psychology.