A horseshoe is a U-shaped item made of metal or modern synthetic materials and then nailed or glued to the hooves of an animal, usually a horse. It's meant to protect the horse's feet from wear and tear, just like a shoes does for a human. Professional horseshoers are called 'farriers''. They place the horseshoes on the outside surface of the hoof by nailing through the insensitive hoof wall (which is like the human toenail only much larger and thicker.)
Horseshoes are often kept as a talisman and said to bring good luck in many cultures. A common tradition is that if a horseshoe is hung on a door with the two ends pointing up,good luck will happen. If placed with the ends down, bad luck will occur. Other traditions say it doesn't matter how the horseshoes is hung, so long as it has been worn by horse already, found and not purchased, and can be touched. In almost all traditions, luck is contained in the shoe and can pour out through the ends.
One reputed origin of the tradition of lucky horseshoes is the story of Saint Dunstan and the Devil. Dunstan, who became the Archbishop of Canterbury in AD 959, was a blacksmith by trade. The story relates that he once nailed a horseshoe to the Devil's hoof when he was asked to re-shoe the Devil's hoof. This caused the Devil great pain, and Dunstan only agreed to remove the shoe and release the Devil after the Devil promised never to enter a place where a horseshoe is hung over the door.
Another theory concerning the placing of horseshoes above doorways is to ward off fairies. The theory was that fairies are repelled by iron and as horseshoes were an easily available source of iron, they could be nailed above a door to prevent any unwanted, otherworldly guests. One can see how the custom, as people began to forget the stories concerning the Fair Folk, eventually morphed into a simple good luck charm.
Horseshoe tattoos can stand alone as a symbol of good luck or may be incorporated with other good luck tattoos, such as four-leaf clovers and dice. Horseshoe tattoos can also be symbols and talismans of fertility.
