Iron-hulled sailing ships represented the final evolution of sailing ships at the end of the age of sail. They were built to carry bulk cargo for long distances in the nineteenth and early twentieth centuries. They were the largest of merchant sailing ships, with three to five masts and square sails, as well as other sail plans. They carried lumber, guano, grain or ore between continents. Later examples had steel hulls. They are sometimes referred to as "windjammers" or "tall ships". Several survive, variously operating as school ships, museum ships, restaurant ships, and cruise ships.

A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships carry square sails on each mast—the brig and full-rigged ship, said to be "ship-rigged" when there are three or more masts. Others carry only fore-and-aft sails on each mast, for instance some schooners. Still others employ a combination of square and fore-and-aft sails, including the barque, barquentine, and brigantine.