COIN: A piece of metal or, rarely, of some other material (such as leather or porcelain) certified by a mark or marks upon it as being of a specific value. Coinage is considered to be any standardized series of metal tokens, their specific weights representing specific values, and usually stamped with designs and inscriptions. Coins or coinlike objects were first issued by the Lydians of Anatolia in the late 7th century bc, made of the gold–silver alloy electrum. Their use was then adopted in the Far East, then around the Mediterranean, and has since spread throughout the world. Early coins were used for specialized, prestigious purposes and not for everyday exchange. The early Greek coins were also made of electrum, silver, or gold; the first Roman coins were produced in the early 3rd century bc and were also made of precious metals. Later in that century the first bronze coin was introduced. These material remains are self-dating, though they do not always date the materials they are found with as they may have been traded, handed down through generations, or displaced in the stratigraphy
of a site.