In June, Apple announced that Apple Pay would support person-to-person payments—and named it Apple Pay Cash—as a way for iOS users to send and receive money to each other via iMessage or Siri, for instance. This feature is similar to the one already offered by services like Venmo or PayPal, that allow users to transfer money at no cost.1
Juli Clover has listed all the ways Apple Pay Cash can be used:
Apple Pay Cash, Apple's peer-to-peer payments service, became available for developers and public beta testers in the United States this morning with the release of the second iOS 11.2 public beta.
Even though Apple launched this in public beta today it won't be available for all users (but developers) until the release of iOS 11.2 later this year.2
Transferring money with credit cards does cost money. ↩