The operation of the cards provides an agreement between an issuer, an operator and a circuit of payment:

• Issuing entity is the company who shall issue a credit card (bank or private company). The issuing company defines a loan agreement with the holder of the card, customers considered the company’s employees and anyone who spends money through the use of the card;
• Body operator is the business that, by joining a circuit of payment, allowing its customers to pay through the means of payment arrangement, an alternative to cash. Membership of the circuit is usually through the intermediary of management company terminals (such acquirer), which offers services such as the sale or rental POS;
• Circuit of payment: the company is to carry through its own network of communication, requests and authorizations for the corresponding expense. The network is expanding the circuit through the delegates to the acquirer to install POS (network termination) with new merchants. The major world circuits are Visa, MasterCard, Diners and American Express.
• As well as the payment instrument, the card can be used as a tool for drawing all’ ATM (simulating an ATM card through the secret code delivered with the paper).