In the study of numismatics, tokens are coin-like objects used instead of coins. The field of tokens is part of exonumia. Tokens are used in place of coins and either have a denomination shown or implied by size, color or shape. "Tokens" are often made of cheaper metals: copper, pewter, aluminium, brass and tin were commonly used, while bakelite, leather, porcelain, and other less durable materials are also known.