A magnetic stripe reader is a device that reads the information stored on the magnetic stripe of cards, such as credit cards or identification cards. The magnetic stripe contains encoded data that includes details like the card number, expiration date, and cardholder's name. When the card is swiped through the reader, the device interprets this data for processing transactions or verifying identity. These readers are commonly used in various settings, including retail stores, ATMs, and access control systems. They work by using magnetic sensors to detect the changes in magnetic fields as the card moves past, allowing for quick and efficient data retrieval.