Mating

In biology, mating is the pairing of opposite-sex or hermaphroditic internal fertilization animals for copulation and, in social animals, also to raise their offspring. In some birds, for example, it includes nest-building and feeding offspring. The human practice of making domesticated animals mate and of artificially inseminating them is part of animal husbandry.

Copulation
Copulation is the union of the external sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization. The two individuals may be of opposite sexes or hermaphroditic, as is the case with, for example, snails.

Animals initially lived only in water and reproduced by external fertilization in the water. Certain animals started migrating from oceans to the land during the Late Ordovician epoch about 450 million years ago, necessitating internal fertilization to maintain gametes in a liquid medium.

In insects, the male uses its aedeagus to deposit a capsule of spermatozoa, called a spermatophore, into the female's ovipore.

Many other animals reproduce sexually with external fertilization, including many basal vertebrates. Many vertebrates (such as reptiles and most birds) reproduce with internal fertilization through cloacal copulation (see also hemipenis), while mammals copulate vaginally.

In humans, copulation may or may not be related to reproduction. See also sexual intercourse and human sexual behavior.