Abstract Payments are absolutely essential to an economy, and they come in two types. Cash, checks, debit and credit cards are used to make retail or consumer payments at the point of sale while automated clearing houses (in the US) and giro networks (in Europe) along with mailed checks are used for bill payments and employee disbursements. Retail transactions have a small value but their annual transaction volume is in the billions. Wholesale or business transactions use giro and wire transfer networks to make almost all large-value business, government, and financial market transactions. Although the volume of wholesale transactions is small, their daily value is in the trillions. International transactions rely on message transfer networks and associated interbank accounting entries. Even though banks are almost the sole supplier of payment services, payment costs have been falling due to greater use of cheaper electronic instruments as well as economies of scale.