Plantar warts are marked by a hard, horny, rough surfaced area on the sole of the foot. They are more commonly known as verrucas, are caused by the papillomavirus, and can occur both singularly or in clusters. Plantar warts can cause discomfort when walking, as they are flattened and forced into the skin. The infection is commonly spread in swimming pools and communal showers.
As with most types of warts, many plantar warts disappear without treatment, though some may be persistent for years at a time, or disappear for a short while before returning. Removal can be done by cryosurgery, with plasters or gel which contain salicylic acid, or through other chemical treatments.