The Latin term genitalia, sometimes anglicized as genitals, is used to describe the externally visible sex organs: in male mammals, the penis and scrotum; and in female mammals, the vulva and its organs.
The genitals and the internal sex organs are referred to as the secondary sex organs. The primary sex organs are the gonads, a pair of sex organs, specifically the testes in the male or the ovaries in the female. Gonads as primary sex organs, generate reproductive gametes containing inheritable DNA. They also produce most of the primary hormones that affect sexual development, and regulate other sexual organs and sexually differentiated behaviors.
In general zoology, given the great variety in organs, physiologies, and behaviors involved in copulation, male genitalia are more strictly defined as "all male structures that are inserted in the female or that hold her near her gonopore during sperm transfer"; female genitalia are defined as "those parts of the female reproductive tract that make direct contact with male genitalia or male products (sperm, spermatophores) during or immediately after copulation".