Calluses are thickened, hardened areas of skin that develop as a result of repeated friction, pressure, or irritation. They form as the skin's natural defense mechanism to protect underlying tissues from damage. Common causes include frequent use of tools, walking or running in poorly fitting shoes, and repetitive actions that put stress on the skin.
This condition is common, but it can often be prevented by wearing well-fitting, cushion shoes and using protective padding to reduce friction. If they become problematic or painful, then professional treatment may be required.