Piaget's theory of intellectual development proposes that children progress through four distinct stages as their cognitive abilities develop. These stages include the sensorimotor stage from birth to age 2 where children learn through senses and motor skills, the preoperational stage from ages 2 to 7 where symbolic thought emerges, the concrete operational stage from ages 7 to 11 where logical thought develops, and the formal operational stage from ages 12 to adulthood where abstract reasoning abilities emerge. Piaget believed that intelligence represents an individual's ability to adapt to their environment through cognitive structures called schemas that develop at each stage.