Child begin their journey for adulthood from this teenage.Certain changes in physical parameter and behavior starts from this age onward.child become taller.Hair changes it color from non-pigmented to darker and thicker.It appears in areas in beard,mustache,chest,back and pubic region. Voice begin to sound like adult.
In boys.in addition to the above changes,testis and penis become thicker and larger.
In girls.menstruation is the 1st manifestation of puberty beginning and breast is also become enlarging.
Some not acceptable changes also develop due to hormonal influence,like acne vulgaris or hirsutism.