Children undergo rapid changes in physiological, psychological and social functions as well as body structure between 10-19 years of age. These developmental changes are dictated by hormonal changes and are a sign of transition from childhood to adulthood.
These changes include appearance of secondary sex characters, increase in body size and eventual development of reproductive capacity.
Recent studies show an earlier onset of puberty (breast enlargement) in girls from 11 years to 10 years now. Similar trend has also been noted in boys.