Payment gateways in shopping carts facilitate secure transactions between the customer and the merchant. They act as intermediaries between the customer's payment information and the merchant's payment processing system. When a customer makes a purchase, the payment gateway performs the following steps:

Authorization request: The customer's payment information is sent to the payment gateway for authorization.

Verification of payment information: The payment gateway verifies the customer's payment information, including the credit card number, expiration date, and security code.

Communication with the acquiring bank: The payment gateway communicates with the acquiring bank to determine if the customer's account is valid and has sufficient funds to cover the purchase.

Authorization response: The payment gateway sends an authorization response to the shopping cart indicating whether the transaction is approved or declined.

Payment processing: If the transaction is approved, the payment gateway processes the payment, transferring the funds from the customer's account to the merchant's account.

Confirmation and receipt: The customer receives a confirmation of the purchase and a receipt of the transaction.

The payment gateway acts as a secure bridge between the customer's payment information and the merchant's payment processing system, ensuring that the customer's information is protected and that the transaction is processed accurately and securely.