Adolescence begins at age 11 and lasts until age 21, which marks the beginning of early adulthood. Adolescence covers the teenage years and spans the same time period for boys and girls, even though girls mature physically and developmentally more quickly than boys of the same age. Several key biological and psychological changes take place throughout adolescence, including the onset of puberty.
The general term of adolescence describes a certain period of growth, but breaks down into three distinct categories: early, middle and late adolescence. Early adolescence includes the ages of 11 through 14, while middle adolescence covers ages 15 through 17 and late adolescence includes the ages of 18 through 21.