Seigniorage
Seigniorage , also spelled seignorage or seigneurage (from Old French seigneuriage 'right of the lord (seigneur) to mint money'), is the profit a government makes from issuing currency, which is the difference between the face value of money and the cost of producing it. The term historically referred to a lord's right to mint coins, but today includes revenue from creating coins and banknotes, and interest earned by the central bank from its conduct of monetary policy.