A card reader is a device that allows users to read data from various types of cards, such as credit cards, debit cards, and identification cards. It typically connects to a computer or mobile device and uses magnetic stripes, chips, or contactless technology to access the information stored on the card. These devices are commonly used in retail environments for processing transactions, as well as in security systems for accessing restricted areas. Many modern card readers also support mobile payment options, enabling users to make purchases using their smartphones or smartwatches, enhancing convenience and efficiency in financial transactions.