The gold standard is a monetary system in which the standard economic unit of account is a fixed weight of gold. Under the gold standard, currency issuers guarantee to redeem notes, upon demand, in that amount of gold. Governments that employ such a fixed unit of account, which will redeem their notes to other governments in gold, share a fixed-currency relationship. The gold standard is not currently used by any government or central bank, having been replaced completely by fiat currency. However, private currency, backed by gold, is in use.