Wire rope is a type of cable which consists of several strands of metal wire laid (twisted) into a helix. The term cable is often used interchangeably with wire rope. However, in general, "wire rope" refers to diameter larger than 3/8 inch (9.52 mm). Sizes smaller than this are designated cable or cords. Initially wrought iron wires were used, but today steel is the main material used for wire ropes.