sexual intercourse
Sexual intercourse is a method of natural reproduction. It is usually used for humans, and in the case of humans and other insects and animals, it is defined as mating. Biological reproduction has been transformed and adapted to a given environment in the process of biological evolution. Reproduction methods vary widely, from the proliferation of individuals through cell division to self-fertilization and fertilization, to the way in which male and female directly or indirectly relate to each other. In the animal kingdom, except for a few other species, male and female mate and participate in reproductive activities. Reproductive behavior generally refers to the contact and association between male and female reproductive organs, and the essence of reproductive behavior is that a female receives sperm from a male for the purpose of fertilization of the egg. When a man reaches his or her age, most of the reproductive activities are performed. This is called sexual intercourse or sexual intercourse. Male reproductive organs are inserted into and contacted with female reproductive organs, and sperm and egg are modified in female genitalia .