Warts are small skin growths caused by the human papilloma virus (HPV), which infects the top layer of skin. There are more than 40 different types of HPV. The wart virus can be transmitted from one person to another either by direct contact, or indirectly when both people come in contact with a surface, such as a floor or desk.
People may come into contact with HPV by walking barefoot in public places, such as gyms and shower floors. HPV also can be transmitted in the same person from one spot on the body to another. It is easier for HPV to infect a person when the person's skin is scratched or cut.
Warts can appear at any age but are more common in older children and are uncommon in the elderly. A wart's appearance varies with its location and the type of virus that has caused it. For example, flat warts commonly appear on the face, neck, chest, forearms and legs. Most warts go away after a year or two, but some last for years or come back after going away.
Warts can itch or bleed. When warts are located in areas that are rubbed against clothing or bumped frequently, they can become irritated and the skin around them can become painful.