Frogs are amphibians. Some live in water, while others live on land, or both.
Frogs go through a life cycle. A frog starts out as an egg surrounded by a jelly-like substance in water.
Then it forms into a water-breathing tadpole inside the egg. Then it hatches.
Then it forms arms and legs. Its tail becomes smaller and smaller as it grows into an air-breathing froglet.
Its tail soon disappears and now it is an adult frog. The frog mates and a female lays eggs on it's own.
The life cycle repeats itself.