Allogamy occurs when the gametes which join together during fertilization come from two different individuals. The female gamete is usually in the form of an egg or ovum while the male gamete takes the form of a sperm.
Autogamy, also known as self-fertilization or self-pollination, is the fusion of male and female gametes, which are produced by a single individual. Species which are able to produce both male and female gametes are called hermaphrodites.
Another two types of sexual reproduction, mainly seen in animals ; namely internal fertilization and external fertilization.