"There are at least five known types of warts that are caused by a number of HPV strains: common warts (often found on the hands and scalp); filiform warts (common in those who are overweight and often appear on the face and armpits); periungual warts (usually appearing around the fingernails); flat warts (smaller than the common warts and appear in clusters on the hands and legs); and plantar warts."