Frogs and toads (Anura) are one of three main groups of amphibians, the other two being newts and salamanders and caecilians. There are about 4,380 species of frogs and toads, making the Order Anura the most diverse of all the amphibian groups. More than 80 percent of all frogs and toads occur in the tropics. Frogs and toads inhabit a wide range of habitats including deserts, mountains, forests, and savannas.
Frogs and toads are easily distinguished from other amphibians because they have no tail, a large head with large eyes, and most importantly, they have long, powerful hind legs that are in many species fine-tuned for jumping. The backbone of frogs and toads usually consists of 12 or fewer bones. That of newts and salamanders has between 30 and 100, while caecilians can have as many as 250 bones in their backbone.
The terms "frog" and "toad" are informal and do not reflect any underlying taxonomic differences. In general, the term toad is used to apply to anuran species that have rough, warty skin. The term frog is used to refer to anuran species that have smooth, moist skin. These terms can be misleading though, because the definitions of the terms "frog" and "toad" vary in different parts of the world.
Frogs and toads are divided into three groups, the old frogs, middle frogs and new frogs.