Apple Pay Cash has arrived to US customers, enabling person to person cash payments through Apple Pay and iMessage.
The feature was first supported in the iOS 11.2 beta 2 but was not ready by the time the final iOS 11.2 rolled out a few days ago.
Apple Pay Cash supports iPhone SE, iPhone 6 and newer, iPad Pro, iPad 5th Generation, iPad Air 2, iPad mini 3 (or later) while Apple Watch users need watchOS 4.2 to use Apple Pay Cash.
You need to restart your devices before they can start to send and receive money.
Currently a US exclusive, there’s no timeframe for the eventual international rollout.