<P> A credit card is a payment card issued to users (cardholders) to enable the cardholder to pay a merchant for goods and services based on the cardholder's promise to the card issuer to pay them for the amounts so paid plus the other agreed charges . The card issuer (usually a bank) creates a revolving account and grants a line of credit to the cardholder, from which the cardholder can borrow money for payment to a merchant or as a cash advance . In other words, credit cards combine payment services with extensions of credit . Complex fee structures in the credit card industry may limit customers' ability to comparison shop, helping to ensure that the industry is not price - competitive and helping to maximize industry profits . Due to concerns about this, many legislatures have regulated credit card fees . </P> <P> A credit card is different from a charge card, where it requires the balance to be repaid in full each month . In contrast, credit cards allow the consumers a continuing balance of debt, subject to interest being charged . A credit card also differs from a cash card, which can be used like currency by the owner of the card . A credit card differs from a charge card also in that a credit card typically involves a third - party entity that pays the seller and is reimbursed by the buyer, whereas a charge card simply defers payment by the buyer until a later date . </P> <P> The size of most credit cards is 85.60 mm × 53.98 mm (​ 3 ⁄ × ​ 2 ⁄ inches) and rounded corners with a radius of 2.88--3.48 mm, conforming to the ISO / IEC 7810 ID - 1 standard, the same size as ATM cards and other payment cards, such as debit cards . </P> <P> Credit cards have a printed or embossed bank card number complying with the ISO / IEC 7812 numbering standard . The card number's prefix, called the Bank Identification Number, is the sequence of digits at the beginning of the number that determine the bank to which a credit card number belongs . This is the first six digits for MasterCard and Visa cards . The next nine digits are the individual account number, and the final digit is a validity check code . </P>

What is the mm on a credit card