Last year Paypal partnered with Facebook Messenger to allow users of the Facebook instant messaging application to make purchases through Messenger and in turn to create a communication channel for Paypal users. Now they offer peer-to-peer (P2P) payment service directly in Messenger.
Which means Facebook users can send and receive money through chat Messenger using Paypal as their funding source. This service is launched for users in the United States only. It is not yet confirmed when this service will be activated for all other regions of the world.