The Pay API operation is used to transfer funds from a sender's PayPal account to one or more receivers' PayPal accounts. You can use the Pay API operation to make simple payments, chained payments, or parallel payments; these payments can be explicitly approved, preapproved, or implicitly approved. Parallel payments are useful in cases when a buyer intends to make a single payment for items from multiple sellers. Examples include the following scenarios: a single payment for multiple items from different merchants, such as a combination of items in your inventory and items that partners drop ship for you. purchases of items related to an event, such as a trip that requires airfare, car rental, and a hotel booking.