Calluses occur on the feet, between the toes, on the sides of the toes and under the toes. A callus is an area of hard and thickened skin. Usually, a blister first appears, then a callus, and, if the callus is not removed, a corn can also occur in the same area. Calluses most often occur due to footwear that is too tight.
Even if they are not painful, calluses must be removed. Very often, a corn will occur in that same spot, and removing a corn takes much longer.