leather, skin or hide of animals, cured by tanning to prevent decay and to impart flexibility and toughness. Prehistoric and primitive peoples preserved pelts with grease and smoke and used them chiefly for shoes, garments, coverings, tents, and containers. Today pelts are prepared for tanning by dehairing, usually with lime, followed by fleshing and cleaning. After tanning, leather is generally treated with fats to assure pliability. The practice of shaving leather to the required thickness was abandoned early in the 18th cent. after the invention of a machine that split the tanned leather into a flesh layer and a grain (hair-side) layer; skivers are thin, soft grains used for linings and for covering firm surfaces. Characteristic grains may be brought out by rubbing, as in morocco leather (goatskin), or may be imitated by embossing. Finishes include glazing, a high glaze being achieved by rolling with glass cylinders; coloring with stains or dyes; enameling or lacquering as for patent leather; and sueding, buffing with emery or carborundum wheels to raise a nap, usually on the flesh side. Russia leather, originally vegetable-tanned calfskin dressed with birch oil that imparted a characteristic odor and often dyed red with brazilwood, is a term now covering a number of variants. Rawhide is similar to parchment and is untanned. Cordovan, or Spanish, leather, a soft, colored leather made at Córdoba during the Middle Ages and often richly modeled and gilded, is imitated for wall coverings, panels, and screens. Leather is much used in bookbinding. Artificial leather, made since about 1850, was originally a strong fabric coated with a rubber composition or with a synthetic substance such as pyroxylin. Since World War II, materials made from vinyl polymers have far outstripped the earlier artificial leathers in commercial importance.