A frog is a vertebrate and cold-blooded amphibian belonging to the order Anura. There are about 4,800 described species of frogs. They vary in size, ranging from 7.7 mm to 300 mm. An adult frog is characterized by a short body, long hind legs, protruding eyes, and webbed digits. It has a soft, smooth skin, covered with moist slime, mucus.