Let’s say you buy a laptop online with a Mastercard issued by Wells Fargo. You submit your payment details, which typically include the card number, the expiration date, your name and address, and maybe the CCV code.
When you submit that information, it is sent directly to the payment gateway. The transmission usually occurs over a secure network, such as a TLS (Transport Layer Security) or SSL (Secure Sockets Layer). When the payment gateway software receives the payment details, it encrypts them and sends the data onto the next link in the chain, which is the merchant’s processor.
Eventually (we’re talking about seconds or less), the transaction is approved or rejected by the issuing bank. If it’s approved, the transaction is sent back to the payment gateway, which transmits it back to the website.