Jean Piaget (1896–1980) was a Swiss psychologist and epistemologist renowned for his pioneering work in child development. He is best known for his theory of cognitive development, which outlines how children progress through distinct stages of thinking as they grow. Piaget's research emphasized that children are active learners who construct knowledge through interaction with their environment. His groundbreaking work has had a profound influence on education, psychology, and understanding how humans acquire knowledge.