A frog is an amphibian, a type of cold-blooded vertebrate animal that typically has smooth, moist skin, no tail, and strong hind limbs adapted for jumping and swimming. Frogs belong to the order Anura, which is characterized by these features. They live both in water and on land and undergo a life cycle that includes metamorphosis from a tadpole (larval stage) to an adult frog. Frogs are distinct from reptiles and mammals by their amphibious nature and specific biological traits.