Merchants universally accept cash. Consumers widely hold cash but also carry debit and credit cards. The cost of using a method of payment has only a small influence on which method consumers use. Large merchants accept all payments, while only two-thirds of small and medium-sized businesses accept credit cards. Merchants report that credit cards are the costliest payment method compared with cash and debit cards. However, costs are not the only consideration. Merchant acceptance of credit accounts for the many con-sumers that want to use credit cards. This interaction between consumers and merchants is known as network externalities.