Selective breeding (also called artificial selection ) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics ) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties , cultigens, or cultivars. Two purebred animals of different breeds produce a crossbreed . Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals.