Hint: Adolescence is a stage puberty which is related to the growth of individuals and the definition will be related to the starting of growth period.
Adolescence is a period when puberty starts during which a young person starts to grow and develops from a child into an adult. There is physical and psychological development seen. It is kind of a transitional period between childhood and adulthood. The purpose is development of the children for adult roles.
The average age of starting puberty is seen at the age of 11 for girls and at the age of 12 for boys. It depends on person to person as puberty is influenced by heredity and environmental factors such as diet and exercise. These factors play important in this as it can also delay puberty. Usually it involves changes in individuals' height, weight, body composition. Hormones also play an important role as these are responsible for the body to behave once the puberty begins. It triggers the behavioural and physical changes.
In males, there is appearance of secondary sex characters like a deeper voice and development of large Adam's apple, growth of beard or you can say overall body hair. In females, there is development of breasts, curved hips. This is a hormonal imbalance towards an adult state in both the males and females. The pituitary gland secretes hormonal agents into the bloodstream which activates the male and female gonads and it further puts these gonads into a state of rapid growth and development. Then these gonads produce a mass production of hormones. The testosterone which is male sex hormone is produced by testes and oestrogen which is female sex hormone and that is produced by the ovaries in male. The production of sex hormones in both and females get increased until sex maturation is met.
Some males do not develop the maleness features but instead of that they develop female features due to the imbalance in the sex hormones and obesity. Breast development is seen and this is called gynecomastia.
Note: It is a period of onset of puberty which is seen between childhood and adulthood. There are so many changes seen in this period. There is development and growth of the body of both male and females and the physical appearance also gets changed.