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.

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.