A consumer with an unused line of credit on his or her credit card account may make retail purchase without presenting a demand deposit check or cash. Unutilized credit card credit is used instead. The line of unutilized credit available to card holders may be a good candidate for inclusion in the definition of money. These credit lines serve as a medium of exchange for the purchase of a wide variety of goods and services. Lines of unutilized credit card credit are similar to unutilized demand deposit overdraft facilities, which allow customers to issue checks for more money than they have on deposit. Overdrafts, which have long been used in Great Britain and Canada, are now widely used in the Unite States, often against bank credit card credit. The range of transactions that might be included in computerized credit card transactions is large. Taxicabs, newspaper stands, vending machines, public transportation, street vendors, and highway toll stations, to name but a few places where cash is used, could all, be provided with small machines that store information about purchases. These data sources could be linked into computer terminals at convenient locations or could be entered synchronously with the purchase through centralized communication networks. A centralized electronic funds transfer system could even instantaneously charge the purchases against the buyers' bank accounts and credit the funds to the sellers bank accounts. Both lines of unutilized credit card credit and unutilized demand deposit overdraft facilities allow customers to use more money than they have on deposit.