Calluses are thick patches of skin that can grow on your feet. They form naturally from dead layers of skin that are subjected to friction and pressure and typically form on the weight-bearing areas of your feet, such as the big toe, heel, ball, or side of your foot. Some amount of callouses are normal, but they typically grow worse over time if not treated. You can also prevent calluses from forming, or returning by wearing proper shoes and applying a cream to the feet daily.