The most extensively used of all alloys are those consisting mainly of copper. Their ornamental appearance and non-corrosive quality make them desirable, and their strength, with varying degrees of hardness, elasticity, ductility and malleability, supplies the requirements for materials of a wide range of use.

In general, copper-zinc alloys are called brass, although some brass may contain also a small amount of lead or tin; copper-tin alloys are the main constituents of bronze; and copper-tin-zinc alloys are known as composition. These terms, as will be learned, are loosely used in practice and not confined to the designations here given.