A frog is a small amphibian with smooth, moist skin, bulging eyes, and powerful back legs built for jumping. Frogs live part of their lives in water and part on land. They start as tiny tadpoles swimming in ponds, breathing through gills like fish. Then, in one of nature's most remarkable transformations, they grow legs, absorb their tails, develop lungs, and hop onto shore as adult frogs.

Most frogs are excellent jumpers because of those muscular back legs. Some can leap twenty times their own body length. They catch insects with long, sticky tongues that shoot out faster than you can blink. Frogs make distinctive croaking sounds, especially during mating season, when male frogs call out to attract females.

The word frog also appears in some expressions: when someone has a frog in their throat, their voice sounds croaky and rough, usually from a cold or from not speaking for a while. Divers sometimes wear rubber suits with flippers called frogman suits because they make swimmers look a bit like frogs in the water.