U-shaped metal plate by which horses' hooves are protected from wear on hard or rough surfaces. Horseshoes apparently are a Roman invention; a mule's loss of its shoe is mentioned by the Roman poet Catullus in the 1st century BC.

The density and insensitivity of the hoof makes it feasible to attach shoes securely by nailing. The craft of the smith, or blacksmith, the process of forging and affixing horseshoes, became one of the great staple crafts of medieval and modern times and contributed to the development of metallurgy.