Piaget's Theory of Cognitive Development is a framework that explains how children learn and think as they grow. Developed by Jean Piaget, this theory outlines four stages: sensorimotor, preoperational, concrete operational, and formal operational. Each stage represents a different way of understanding the world, with children progressing through them as they gain new experiences and skills. In the sensorimotor stage, infants learn through their senses and actions. The preoperational stage involves the development of language and imagination 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.