Adolescence is the period between childhood and adulthood that involves physical, cognitive, psychological, social, and spiritual development. Early adolescence occurs around ages 10-13, middle adolescence around ages 14-16, and late adolescence around ages 17-20. However, the timing of adolescence varies between individuals based on genetics, environment, and economic factors. Erik Erikson's stages of psychosocial development identify key conflicts or crises that occur during each life stage, including adolescence, and how their resolution can result in favorable or unfavorable outcomes for personality development.