Chip cards (smart cards) in credit card format are a security device that is easy to transport. In order to be able to use these small computers, however, an appropriate chip card reader is required.

Card readers - specifically chip card readers ("smart card readers") - are devices that control chip cards. In doing so, data is not only read, but also written or applications on the chip card are controlled. This is why one also speaks of chip card terminals.

The devices supply the chip card with power, determine the clock frequency and establish communication according to the parameters supported by the card, which the card communicates to the reader. The host software determines whether read, write or arithmetic commands are sent to the card.