Inbreeding is a term in genetics, meaning the crossing (mating) of closely related animals or plants. Self-fertilisation in plants is the most extreme kind of inbreeding. It is quite widespread in plants which carry both male and female flowers on the same plant. Inbreeding is the opposite of outcrossing, which is the mating of unrelated members of the same species. The combination of inbreeding and outcrossing is a standard method of artificial selection.