The numbers found on credit cards have a certain amount of internal structure, and share a common numbering scheme.

The card number's prefix is the sequence of digits at the beginning of the number that determine the credit card network to which the number belongs. The card number's length is its number of digits.

The prefixes and lengths for the most common card types are:

The credit card was the successor of a variety of merchant credit schemes. It was first used in the 1920s, in the United States, specifically to sell fuel to a growing number of automobile owners. In 1938 several companies started to accept each other's cards.

The concept of paying merchants using a card was invented in 1950 by Frank X. McNamara in order to consolidate multiple cards. The Diners Club produced the first charge card, which is similar but required the entire bill to be paid with each statement; it was followed shortly thereafter by American Express.

Credit card issuers (banks) cover their costs (including the interest costs for the money that is paid to merchants prior to the bank being paid by customers), and earn profits, by:

An example of the front in a typical credit card:
1. Issuing bank logo
2. EMV chip on "smart cards"
3. Hologram
4. Credit card number
5. Card brand logo
6. Expiration Date
7. Card Holder Name
8. contactless chip

A user is issued a credit card after an account has been approved by the credit provider (often a general bank, but sometimes a captive bank created to issue a particular brand of credit card, such as American Express Centurion Bank), with which they will be able to make purchases from merchants accepting that credit card up to a preestablished credit limit.

A credit card system is a type of retail transaction settlement and credit system, named after the small plastic card issued to users of the system. A credit card is different from a debit card in that the credit card issuer lends the consumer money rather than having the money removed from an account. It is also different from a charge card (though this name is often used to describe credit cards by the public) in that charge cards do not extend the user credit -- the charges must be paid each month in full. In contrast, a credit card allows the consumer to 'revolve' their balance, at the cost of having interest charged. Most credit cards are the same shape and size, as specified by the ISO 7810 standard.