Chain is a flexible length of links or rings joined together. The links of a chain are usually made from metal bent into loops, with the ends of each link joined together inside the loop of the next link.
The size of a chain is measured by the thickness of its links. A half-inch chain has links made from a metal rod 1/2 inch (13 millimeters) in diameter. Chains vary in size from small ones used in jewelry to huge ones used in heavy machinery. Iron, steel, brass, and plastic are used to make the stronger chains. Ornamental chains may be made from alloys of gold, silver, or other metals.
The links of chains sometimes consist of several pieces. Roller chains, such as those used on bicycles, are made this way. Chains used in conveyor belts and industrial machinery may be made of cast metal or plastic pieces. In some chains, each link has a metal brace called a stud to make it stronger.
