A wart is an infection caused by a virus, which can invade your skin through small cuts or breaks. Over time, the wart develops into a hard, rough growth on the surface of the skin. A wart is most commonly seen on the bottom of the foot (plantar wart), but can also appear on the top. Children, teens, and people with allergies or weakened immune systems are more vulnerable to the wart virus.
Symptoms: Warts may appear spongy, with tiny red, brown or black spots. They can grow up to an inch or more across, occurring alone or with smaller warts clustered nearby. Warts are sometimes mistaken for corns or calluses. They can persist for years and recur in the same spot. If left untreated, warts can spread to other parts of the foot or even to the hands or other areas of the body.