A callus (or callosity) is a specific toughened area of the skin which has become relatively thick and hard in response to repeated friction, pressure, or other irritation (usually from ill-fitting shoes or high heels). It occurs at a pressure point, such as the top of the toe or under a toe joint.

Corns are usually regular in shape and can be white, gray, or yellow. They most often form on the outside of the first or fifth toes, since this is the point that pressure most often occurs. Corns that form between the toes are called soft corns, and they are not as firm as other corns because of moisture between the toes.