Apple Pay is Apple’s mobile payment system for the iPhone and Apple Watch which supports NFC based contactless transactions. Apple Pay is compatible on all iPhone models since the iPhone 6 (2014).
Contactless NFC Payment Cards
Apple Pay allows users to register their credit cards and bank (debit) cards in the native Apply Wallet app, and then use those cards at NFC enabled payment terminals to pay for purchases. When the payment terminal is ready to accept payment for a purchase, the iPhone is brought in the RF range of the payment terminal, the iPhone detects the RF field and identifies it as a payment terminal and then presents the appropriate bank card to the terminal as if the card itself was used. Apple claims that Apple Pay is accepted at over 85% of retailers in the USA (2021) and is safer and more secure than swipe based contact transactions.
While contactless payments in Apple Pay do use NFC, they do not use NFC tags or the NDEF standard. Contactless NFC cards use their own standards, chips, controllers, encoding and security which is not a part of Connected Things.
It is not possible to clone or copy an NFC credit card with an iPhone.
Exclusive iOS NFC Payment System
Apple Pay is the only iOS mobile payments system that can access the internal NFC controller as Core NFC explicitly does not support payment related Application IDs. This in effect blocks competitors to Apple Pay (Google, banks…) from using the iPhone and Apple Watch as an equivalent contactless mobile payments system. Apple claims it would decrease the security of Apple Pay if they allowed 3rd party access to the NFC controller in the iPhone. Some consider this to be an unfair and/or illegal monopoly and there are several lawsuits and campaigns to change this (read more).