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.
The size of most credit cards is 85.60 mm × 53.98 mm (3 3⁄8 × 2 1⁄8 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.
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.
Both of these standards are maintained and further developed by ISO/IEC JTC 1/SC 17/WG 1. Credit cards have a magnetic stripe conforming to the ISO/IEC 7813. Many modern credit cards have a computer chip embedded in them as a security feature.
In addition to the main credit card number, credit cards also carry issue and expiration dates (given to the nearest month), as well as extra codes such as issue numbers and security codes. Not all credit cards have the same sets of extra codes nor do they use the same number of digits.
Credit card numbers were originally embossed to allow easy transfer of the number to charge slips. With the decline of paper slips, some credit cards are no longer embossed and in fact the card number is no longer in the front.
The concept of using a card for purchases was described in 1887 by Edward Bellamy in his utopian novel Looking Backward. Bellamy used the term credit card eleven times in this novel, although this referred to a card for spending a citizen's dividend from the government, rather than borrowing.