Adolescence is the developmental period between childhood and adulthood, characterized by significant physical, cognitive, and emotional changes. This period includes early (10-12 years), middle (15-17 years), and late adolescence (18-21 years), and is crucial for identity formation, autonomy, and intimacy. Cognitive abilities advance with increased abstract thinking and decision-making, while social influences, peer relationships, and emotional complexities heighten during this transitional stage.