Whenever an article is generally acceptable in exchange in a community so that B will take it from A in exchange for what A wants, not because B desires the article but because he knows that practically all other persons will take it from him in exchange for the things which they have and which he wants, that article is money; or, to put it more briefly, any commodity which is generally acceptable as a medium of exchange is money.

The term money is sometimes used in other senses. For example, some authors mean by money what we shall call standard money. In this sense gold coin would be the only money in the United States at the present time. Lawyers sometimes define money as legal tender. In this sense gold coins, silver dollars, subsidiary coins, and greenbacks are money, but not silver certificates nor gold certificates.