Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Adolescent psychology addresses the psychological issues and interests of adolescents.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 nineteen 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