Warts
Do you have a rough patch on the sole of your foot that is painful when pressure is applied? If so, it may be a foot wart. A foot wart is also known as a verruca.
Warts are usually harmless. However, they can be a nuisance on the soles of your feet, as you put pressure on them with every step.

What is it?
A wart is a thickening of the skin. This thickening is caused by a virus. On the sole of the foot, a wart often grows inwards, as pressure is exerted on it whilst standing and walking.
A plantar wart may resemble callus or a corn. Sometimes small dark spots are visible within the wart.