Jean Piaget was a Swiss philosopher and psychologist who introduced a theory of cognitive development like Sigmund Freud Jean thought human development can be described in stages (of course leaving the sexuality part of Freud out). The stages are:
Sensorimotor. Birth through ages 18-24 months (Explorer)
Preoperational. Toddler-hood (18-24 months) through early youth (age 7)
( children learn to think abstractly, understand symbolic concepts, and use language etc.)
Concrete operational. Ages 7 to 12 (Understanding complexities)
Formal operations: Pre-adulthood through adulthood (Hypothetical, and theoretical reasoning)
Shoutout to @Ahmedisaal
Have an amazing day!