A payment gateway helps connect the customer's payment interaction with the systems handling the transaction. It may be supplied alongside processing and other services under a single provider brand.
What it does not prove Adding a gateway integration does not guarantee merchant approval, completed settlement or an account balance available to spend. Those are separate parts of the payment relationship.
A practical example A customer enters payment details in a hosted checkout. The store needs the resulting provider confirmation to update the order correctly. Reaching a return page alone should not be treated as proof that payment succeeded.
What to review Check supported methods, authentication, error handling, refunds and how the integration handles customer data. Outsourcing collection can reduce exposure, but the merchant still needs to understand applicable security responsibilities.
Choose the gateway as part of a complete flow: customer payment, reliable order status, fulfilment, refunds and settlement reporting. A good looking checkout is useful only when the surrounding operation works consistently.
Sources and scope
General information, not advice for your individual legal or tax position. Confirm current requirements with the relevant authority or provider.