Frogs are found all over the world, except in Antarctica. They require moisture and usually live in quiet freshwater or in the woods.
Some frogs are highly aquatic, while others are better adapted to terrestrial habitats.
Among the latter type, those with stout bodies and thick skins are often called toads , although the name toad is sometimes restricted to members of the most terrestrial family of the Anura, the Bufonidae. Frogs lack tails in their adult stage. The skin is smooth, usually some shade of green or brown, and often spotted. The bulging eyes have nictitating membranes to keep the eyes moist. Adult frogs have lungs, but their breathing mechanism is poorly developed.