Adolescence is the time between the beginning of sexual maturation (also known as puberty, from the Latin pubertas, meaning adult) and the beginning of adulthood. Adolescence usually spans the years between ages 13 and 19. Adolescence includes physical growth and emotional, psychological, and mental change. Psychological maturation occurs as the child acquires adult-like behavior. During this period, adolescents are expected to become capable of adult behavior and response. Adolescence is a period of many transitions. During the teen years, adolescents experience changes in their physical development at a rate of speed unparalleled since infancy. Physical development includes rapid gains in height and weight. During a one-year growth spurt, boys and girls can gain an average of 4.1 in. (10.4 cm) and 3.5 in. (8.9 cm) in height, respectively. This spurt typically occurs two years earlier about for girls than for boys. Weight gain results from increased muscle development...