Piaget's theory of cognitive development outlines 4 stages of development: 1) Sensorimotor stage (0-2 years) where children learn through senses and motor skills and develop object permanence 2) Preoperational stage (2-7 years) where children's thinking is perceptual but they gain language skills and egocentrism 3) Concrete operational stage (7-11 years) where logical thinking of concrete objects develops along with classification and seriation abilities 4) Formal operational stage (11-adult) where abstract, hypothetical and systematic thinking abilities emerge.