What is Apple Pay and how does it work?

To use Apple Pay for purchases in-store, you must first add your eligible debit or credit card(s) on your device using the Wallet app.
 
To pay using Touch ID, hold your device near the contactless reader. Then, place your finger on “Touch ID” and hold the iPhone near the reader until you see “Done” and a checkmark on your screen which indicates that your payment is complete. If “Touch ID” doesn’t work, or you do not have it enabled, you will need to enter your device passcode.
 
To pay using Face ID, double-click the side button. Glance at your iPhone to authenticate with Face ID. Hold your device near the contactless reader until you see “Done” and a checkmark on the screen which indicates that your payment is complete.
 
To use Apple Pay for purchases within participating merchant apps (or in-app), you must first add your eligible card by going to “Settings” opening “Wallet & Apple Pay” and selecting “Add Credit or Debit Card.”