Apple Pay works with iPhone 6 and later in stores, apps, and websites in Safari; with Apple Watch in stores and apps; with iPad Pro, iPad Air 2, and iPad mini 3 and later in apps and websites; and with Mac in Safari with an Apple Pay enabled iPhone 6 or later or Apple Watch. For a list of compatible Apple Pay devices, see https://support.apple.com/km207105
Other helpful FAQs.
No, your card details are not stored on the device or in the Cloud. When a card is added to Apple Pay, a Device Account Number replaces the need for the card number.
The Device Account Number is used to make secure purchases in stores and within apps and websites. It will not work if it is compromised in any way and cannot be used outside of the device it is assigned to.
The Device Account Number can be found by opening the Wallet app and tapping the (i) symbol in the bottom right corner and then scrolling down to find Device Account Number.
No, it does not cost you anything extra to use Apple Pay.
The usual credit or debit charges apply to purchases and some retailers may apply a credit or debit card surcharge to purchases made using any payment method, including Apple Pay, contactless or chip and PIN transactions.
You require an active data plan or Wi-fi connection to add your card to Apple Pay. Based upon your mobile plan and network, additional message and/or data charges may apply.