Puberty is the period of sexual maturation where the body goes through physical and biological changes to become capable of reproduction. It is triggered by hormonal changes that cause development of secondary sex characteristics like growth of breasts and pubic hair. Girls typically start puberty between ages 8-13 while boys start between 9-14. Puberty signs for girls include breast development and menstruation while boys experience growth of genitals and facial/body hair along with voice deepening.