Erik Erikson's theory outlines 8 stages of human development. Adolescence is the stage between childhood and adulthood characterized by physical, cognitive, and social changes. It is a period of "storm and stress" with emotional turmoil. Key challenges of adolescence include developing a sense of identity, gaining freedom from parental supervision, constructive use of leisure time, navigating sexual relationships and peer adjustment, intellectual maturation, vocational choice, emotional maturity, and developing life goals.