Farriers are trained in the art and science of trimming and shoeing horses of all breeds. They trim the hoof to remove extra growth and to align the bone structure of the leg so it meets the ground squarely. The process that farriers use involves removing the old shoe, cleaning out the dead exfoliating material, and then using nippers to remove excess hoof wall growth. The foot is then made flat using the rasp. Horse shoes are shaped to fit the hoof and nailed on. Due to popularity and diverse uses of horses, there is a steady demand for qualified farriers throughout the world.