A card reader is a device that helps people access money from their bank accounts. It works by reading information on a piece of plastic with a magnetic strip (or sometimes a chip) on it. The card reader reads this information from the plastic card, such as your name and account number, and allows you to withdraw cash from an automated teller machine or pay for items at the store. The card reader also allows your bank to keep track of how much money you spend and how often you use the card.