Frogs reproduce sexually, though the fertilization process typically happens outside their bodies. The female lays eggs and the male frog deposits his sperm on them. There are exceptions to the common form of reproduction however, as the West African genus Nimbaphrynoides and the Tanzanian genus Nectophrynoides both reproduce via internal fertilization, with the female delivering baby frogs.
Female frogs can lay up to about 700 eggs at a time, depending on the species. Along with the eggs, females deposit a unique jelly-like substance that becomes swollen once it touches water. Once she lays the eggs, the male frog gets his reproductive organ, the cloaca, as close to her eggs as he can. This is so he can try to fertilize as many as possible with his sperm. He wraps his front legs around the female and positions himself partially on top of her in a position called amplexus. Fertilized eggs become hatchlings, then tadpoles, then adult frogs.