Apple has released iOS 11.2 with support for Apple Pay Cash,7.5-watt charging on compatible devices, and various bug fixes and improvements.
With Apple Pay Cash, Apple Pay users will be able to make and receive payments with friends and family quickly and securely. They can send money and get paid right in Messages, or tell Siri to pay someone, using the credit and debit cards they already have in Wallet.
You can download iOS 11.2 by going to Settings > General > Software Update. Eligible devices include the iPhone 5s and later, the iPad mini 2 and later, the iPad Air and later, and the 6th gen iPod touch.