Apple Pay is a mobile payment and digital wallet service offered by Apple. It allows users to make contactless payments with their iPhone, Apple Watch, iPad or Mac.

To use Apple Pay, users need to add their credit or debit card information in the Wallet app on their device. They can also add loyalty cards, gift cards and other types of payment cards. Once the cards are added, users can make payments by holding their device near a contactless payment terminal and authenticating the payment with their fingerprint, Face ID or a passcode.

Apple Pay uses Near Field Communication (NFC) technology to securely transmit payment information between the device and the payment terminal. The payment information is encrypted and stored on the device's Secure Element, a special chip that provides additional security for payments.

Apple Pay also works for online and in-app purchases. Users can select Apple Pay as a payment method and authenticate the payment with Touch ID, Face ID or a passcode.