Define secondary sexual characters.

During puberty many features develops in boys and girls that help to distinguish male from female, which is called secondary sexual character. This causes changes in boys like production of sperms, growth of beard and moustaches, growth of hair on chest, under the arms and in pubic region, this causes changes in girls like production of ova, development of breast, development of mammary gland inside the breast, growth of hair under the arms and in pubic region.