Callus is hard/thick patches of skin. You are most likely to see callus on the bottom of your foot on the bony areas that carry your weight – your heel, big toe, the ball of your foot and along the side of your foot.
Callus develops from repeated friction, rubbing/irritation and pressure on the skin. It can become uncomfortable over time as it thickens. Cracks (fissures) form in a callus and these can be painful.