A yar is a spar on a mast from which sails are set. It may be constructed of timber, steel, or from more modern materials, like aluminum or carbon fiber. Although some types of fore and aft rigs have yards (see below), the term is usually used to describe the horizontal spars used with square sails. In addition, for some decades after sails were generally dispensed with, some yards were retained for deploying wireless (radio) aerials and signal flags.