A "Refund" operation refers to the process of returning funds to a customer after a transaction has been fully processed and settled. This means that the payment was completed, and now the merchant is giving the money back to the customer, usually due to a return, a canceled order, or an error.

Key points about a Refund operation:

Timing: It happens after the transaction has been fully processed and the funds have already been transferred to the merchant's account.

Result: The customer receives the funds back, either partially or in full, depending on the situation.

Processing Time: Refunds may take a few days to appear in the customer's account, depending on the payment method and the financial institution's processing time.

Refund vs. Void: Unlike a void, where no funds are actually transferred, a refund involves returning money that has already changed hands.

In short, a refund gives the customer their money back after the payment has been completed.