Adolescence is a period of transition between childhood and adulthood that involves physical, cognitive, social and emotional changes. It is initiated by pubertal changes and involves three stages - early, middle, and late adolescence. During this time, adolescents experience rapid physical growth and development of reproductive organs. They also go through significant cognitive, social, and emotional development as they form their identity, become more independent, experience mood swings and stress, and learn to navigate relationships. The physical, social, and emotional changes that occur during adolescence help prepare youth for adult roles and responsibilities.