A toad can refer to a number of species of amphibians in the order Anura. A distinction is often made between frogs and toads by their appearance, prompted by the convergent adaptation among so-called "toads" to dry habitats. Many "toads" have leathery skin for better water retention, and brown coloration for camouflage. They also tend to burrow. However, these adaptations are not reliable indicators of its ancestry. Because taxonomy reflects only evolutionary relationships, any distinction between frogs and toads is irrelevant to their classification.

For instance, many members of the frog families Bombinatoridae, Discoglossidae, Pelobatidae, Rhinophrynidae, Scaphiopodidae, and some species from the Microhylidae family are commonly called "toads". However, the only family exclusively given the common name "toad" is Bufonidae, or the "true toads". Some "true frogs" of the genus Rana have also adapted to burrowing habitats, while a bufonid species in the genus Atelopus are conversely known by the common name "harlequin frogs". Similarly to frogs, toads also display metamorphosis from tadpole to sexually mature adult.