Warts are an infection caused by HPV virus (Human Papilloma Virus) which can invade your skin through small cuts or breaks. This type of wart is considered to be very common, especially among young children or physically active adults.
The most common type of warts found at bottom of the foot is known as a plantar wart or verrucae. Over time, warts develop into a hard, rough growth on the surface of the skin. It can be painful especially when pressure is applied such as walking or running.