Puberty is the juncture between adolescence and youth. The stage at which secondary characteristics develop in male and female bodies and reproductive organs begin to become active is called puberty. Puberty starts at 10-12 years for girls and 13-14 years for boys in tropical countries. Winter starts after 3-4 years in the main country. Puberty transition is called tanner stage. Named after the child-adolescent specialist James M. Tanner.