Samsung Pay is a mobile payment service developed by Samsung Electronics that allows users to make payments using their smartphones. It works by storing credit and debit card information securely on the device, enabling users to pay at various retailers by simply tapping their phone on a payment terminal. The service supports both Near Field Communication (NFC) and Magnetic Secure Transmission (MST) technologies, making it compatible with a wide range of payment systems. Users can also earn rewards and track their spending through the app, enhancing the overall shopping experience.