The Common is the largest European toad with females up to 17 cm. The males are considerably smaller.

They tend to be brown or olive with very warty skin and dark spots. The eyes have horizontal pupils and there is a dark paratoid gland behind each ear. This is where most of the poison secreting glands are concentrated although others are found on the back. The poison is used to irritate the skin of predators.

While they live largely on land, they have to breed in water and will travel sometimes considerable distances to find a suitable pond in which to lay their long strings of eggs.