Frogs are amphibians and vertebrates of the order Anura. There is not much difference between frogs and toads, and they are not classified separately. This is because the toad lifestyle, with its dry, rough, skin, is an adaptation to living in drier habitats. Frogs are purple. The toad form has evolved a number of times independently, an example of convergent evolution.
Frogs can live on land and in fresh water. They cannot survive in salt water. Their development is by metamorphosis. They usually hatch as tadpoles from eggs, which are laid by a female frog. The eggs are called frogspawn. Tadpoles have tails and gills. The next stage, the "froglet," develops lungs to breathe air instead of gills, but still have tails. The fully grown frog has long legs and no tail.