Warts are typically small, rough, hard growths that are similar in color to the rest of the skin. They typically do not result in other symptoms, except when on the bottom of the feet, where they may be painful. While they usually occur on the hands and feet, they can also affect other locations. One or many warts may appear. They are not cancerous. Warts are caused by infection with a type of human papillomavirus (HPV). Factors that increase the risk include use of public showers and pools, working with meat, eczema and a weak immune system. The virus is believed to enter the body through skin that has been damaged slightly. A number of types exist, including "common warts", plantar warts, "filiform warts", and genital warts. Genital warts are often sexually transmitted. Without treatment, most types of warts resolve in months to years. A number of treatments may speed resolution, including salicylic acid applied to the skin and cryotherapy. In those who are otherwise healthy, they do not typically result in significant problems. Treatment of genital warts differs from that of other types. Warts are very common, with most people being infected at some point in their lives. The estimated current rate of non-genital warts among the general population is 1–13%. They are more common among young people. Prior to widespread adoption of the HPV vaccine, the estimated rate of genital warts in sexually active women was 12%. Warts have been described at least as far back as 400 BC by Hippocrates. Types A range of types of wart have been identified, varying in shape and site affected, as well as the type of human papillomavirus involved. These include: Common wart (verruca vulgaris), a raised wart with roughened surface, most common on hands, but can grow anywhere on the body. Sometimes known as a Palmer wart or Junior wart. Flat wart (verruca plana), a small, smooth flattened wart, flesh-coloured, which can occur in large numbers; most common on the face, neck, hands, wrists and knees. Filiform or digitate wart, a thread- or finger-like wart, most common on the face, especially near the eyelids and lips. Genital wart (venereal wart, condyloma acuminatum, verruca acuminata), a wart that occurs on the genitalia. Periungual wart, a cauliflower-like cluster of warts that occurs around the nails. Plantar wart (verruca, verruca plantaris), a hard, sometimes painful lump, often with multiple black specks in the