How Credit Cards Work

Credit cards are issued by a credit card issuer, such as a bank or credit union, after an account has been approved by the credit provider, after which cardholders can use it to make purchases at merchants accepting that card. Merchants often advertise which cards they accept by displaying acceptance marks – generally derived from logos – or may communicate this orally, as in “We take (brands X, Y, and Z)” or “We don’t take credit cards”.

When a purchase is made, the credit card user agrees to pay the card issuer. The cardholder indicates consent to pay by signing a receipt with a record of the card details and indicating the amount to be paid or by entering a personal identification number (PIN). Also, many merchants now accept verbal authorizations via telephone and electronic authorization using the Internet, known as a card not present transaction (CNP).

Electronic verification systems allow merchants to verify in a few seconds that the card is valid and the credit card customer has sufficient credit to cover the purchase, allowing the verification to happen at time of purchase. The verification is performed using a credit card payment terminal or point-of-sale (POS) system with a communications link to the merchant’sacquiring bank. Data from the card is obtained from a magnetic stripe or chip on the card; the latter system is called Chip and PIN in the United Kingdom and Ireland, and is implemented as an EMV card.

For card not present transactions where the card is not shown (e.g., e-commerce, mail order, and telephone sales), merchants additionally verify that the customer is in physical possession of the card and is the authorized user by asking for additional information such as the security code printed on the back of the card, date of expiry, and billing address.

Each month, the credit card user is sent a statement indicating the purchases undertaken with the card, any outstanding fees, and the total amount owed. After receiving the statement, the cardholder may dispute any charges that he or she thinks are incorrect (see 15 U.S.C. § 1643, which limits cardholder liability for unauthorized use of a credit card to $50, and the Fair Credit Billing Act for details of the US regulations). Otherwise, the cardholder must pay a defined minimum proportion of the bill by a due date, or may choose to pay a higher amount up to the entire amount owed. The credit issuer charges interest on the amount owed if the balance is not paid in full (typically at a much higher rate than most other forms of debt). In addition, if the credit card user fails to make at least the minimum payment by the due date, the issuer may impose a “late fee” and/or other penalties on the user. To help mitigate this, some financial institutions can arrange for automatic payments to be deducted from the user’s bank accounts, thus avoiding such penalties altogether as long as the cardholder has sufficient funds.