Warts are one of several lesser afflictions of the foot, which nevertheless can be quite painful.
They are caused by a virus, which typically invades the skin through small cuts and abrasions. They are frequently called plantar warts, because they appear most often on the plantar surface, or sole, of the foot. They can appear anywhere on the skin, however, and technically only those on the sole are properly called plantar warts. Most warts are harmless and benign, even though painful. They are often mistaken for corns, which are layers of dead skin that build up to protect an area which is being continuously irritated, whereas a wart is a viral infection.