Effect of Socio-Economic Status on Nutritional Status on Adolescent Girls of Paschim Medinipur, West Bengal, India.

Teenager, or teen, is a young person whose age falls within the range from 13–19. They are called teenagers because their age number ends with "teen". Usage by ordinary people varies, and also varies in different societies. Most societies traditionallyhad a formal ceremony to mark the change from childhood to adulthood. During puberty, rapid mental and physical development occurs. Adolescence is the name for this transition period from childhood to adulthood.

In the United States, teenagers from the ages 12-14 go to middle school while teenagers from the ages of 14-18 typically go to high school. In the United Kingdom (UK); teenagers and non-teens are mixed in secondary school. Teenagers attending secondary school (high school in the US) generally graduate at the age of 17 or 18. 

On average, girls begin puberty at ages 10-11; boys at ages 11-12. Girls usually complete puberty by ages 15-17, while boys usually complete puberty by ages 16-17. The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average between ages 12-13; for males, it is the first ejaculation, which occurs on average at age 13. In the 21^st century, the average age at which children, especially girls, reach puberty is lower compared to the 19^th century, when it was 15 for girls and 16 for boys. This can be due to improved nutrition resulting in rapid body growth, increased weight and fat deposition, eating meat from animals which have been dosed up with oestrogen. Adolescence can be defined biologically, as the physical transition marked by the onset of puberty and the termination of physical growth; cognitively, as changes in the ability to think abstractly and multi-dimensionally; or socially, as a period of preparation for adult roles.(Read more)