From Wikipedia

The Secret Life Of The Brain

The Teenage Brain

Adolescence, the transitional stage of development between childhood and adulthood, represents the period of time during which a person experiences a variety of biological changes and encounters a number of emotional issues. The ages which are considered to be part of adolescence vary by culture, and ranges from preteens to 19 years. According to the World Health Organization (WHO), adolescence covers the period of life between 10 and 20 years of age. Adolescence is often divided by psychologists into three distinct phases: early, mid, and late adolescence.