A teenager, or teen, is a person who falls within the ages of 13 to 19 years old. The word "teenager" is another word for an adolescent. When a teenager turns 20, they are no longer a teenager: they are no longer in that developmental stage.

The way the word is used varies. Most societies traditionally had a formal ceremony to mark the change from childhood to adulthood. These ceremonies were often quite elaborate.[1] During puberty, rapid mental and physical development occurs. Adolescence is the name for this transition period from childhood to adulthood.

In the United States, children and teens from the ages 11–14 go to middle school, while teenagers from the ages of 14–18 typically go to high school. In the United Kingdom, teenagers and children are mixed in secondary school. Teenagers attending secondary school (high school in the US) generally graduate at the age of 16 or 19. Sexual attraction to teenagers is called ephebophilia, which often gets confused for pedophilia (paedophilia in the UK).[2]

Timing of puberty

On average, girls begin puberty at ages 10–14; boys at ages 12–16.[3][4] Girls usually complete puberty by ages 15–17,[4][5][6] while boys usually complete puberty by ages 16–17.[4][5] The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average between ages 12–13;[7][8][9] for males, it is the first ejaculation, which occurs on average at age 15.[10]In the 21st century, the average age at which children, especially girls, reach puberty is lower compared to the 19th century, when it was 15 for girls and 16 for boys.[11] This can be due to improved nutrition resulting in rapid body growth, increased weight and fat deposition,[12] or eating meat from animals which have been dosed up with estrogen.[13][14]


  1. Huet M. & Savary C. 1995. Africa dances. London: Thames & Hudson. ISBN 0-500-54195-7
  2. DeClue, Gregory. 2009. Should hebephilia be a mental disorder? A reply to Blanchard et al (2008). Archives of Sexual Behavior 38 3, 317-318
  3. "When is puberty too early?". Duke University Hospital. Retrieved October 10, 2012.
  4. 4.0 4.1 4.2 "For girls, puberty begins around 10 or 11 years of age and ends around age 16. Boys enter puberty later than girls-usually around 12 years of age-and it lasts until around age 16 or 17." "Teenage Growth & Development: 11 to 14 Years". pamf.org.
  5. 5.0 5.1 "Teenage Growth & Development: 15 to 17 Years". pamf.org.
  6. "Puberty and adolescence". Retrieved July 5, 2009.
  7. Anderson SE, Dallal GE, Must A (2003). "Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart". Pediatrics 111 (4 Pt 1): 844–50. doi:10.1542/peds.111.4.844. PMID 12671122. 
  8. Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H (2010). "Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth". BMC Public Health (BMC Public Health) 10: 736. doi:10.1186/1471-2458-10-736. PMC 3001737. PMID 21110899. 
  9. Hamilton-Fairley, Diana. Obstetrics and Gynaecology (Second ed.). Blackwell Publishing. http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf. 
  10. (Jorgensen & Keiding 1991).
  11. Alleyne, Richard (2010-06-13). "Girls now reaching puberty before 10 - a year sooner than 20 years ago". The Daily Telegraph. London.
  12. Guillette EA et al (2006). "Altered breast development in young girls from an agricultural environment". Environ. Health Perspect. 114 (3): 471–5. PMC 1392245. PMID 16507474. 
  13. Buck L.G.M. et al (2008). "Environmental factors and puberty timing: expert panel research needs". Pediatrics 121 Suppl 3: S192–207. doi:10.1542/peds.1813E. PMID 18245512. 
  14. Mouritsen A et al (2010). "Hypothesis: exposure to endocrine-disrupting chemicals may interfere with timing of puberty". Int. J. Androl. 33 (2): 346–59. doi:10.1111/j.1365-2605.2010.01051.x. PMID 20487042.