Calluses are areas of skin that grow thick in response to repeated pressure and friction. They are the body's way of protecting its skin, or the structures beneath it, from injury. Calluses will form on the skin of any part of the body that is exposed to excessive pressure or friction. Sometimes calluses are useful. Laborers and people who work hard with their hands typically develop thick calluses that protect their fingers and palms from nicks, scratches and cuts, and anyone who has ever tried to play a stringed musical instrument will tell you it's a painful process until you develop strong calluses on your fingertips.
Calluses Having Calluses elsewhere on the body can be a mixed blessing, however.
The feet are one such area. In parts of the world where people commonly go barefoot for much of the year, for example, a hefty layer of callus along the plantar surface provides a minimally acceptable degree of protection. But in other areas where the wearing of shoes predominates, calluses can become a problem. Calluses typically occur on the sole of the foot, either on the heel or under the five metatarsal heads, the area where the long inner bones of the toes extend into the foot. These two areas typically bear most of the pressure and friction from standing and walking, and respond by growing calluses to protect the skin there.