The diagram below presents the exchange process from the point of view of the buyer.

1. The buyer validates the shopping cart.
2. The merchant website redirects the buyer to the payment gateway.
   This redirection is done via an HTML POST form in HTTPS.
   The parameters of the form are described in the chapter Generating a payment form.
3. When the parameters and their signature have been verified, the payment method selection page appears.
   Figure 1. Selecting a payment method

   If the payment method has been specified in the form, the buyer moves on directly to step 6.

4. The buyer selects a payment method.
5. The buyer enters the number and the expiry date of their card.
   If the card has a security (CVV) code, it must be specified.
   Figure 2. Entering payment method details
6. He or she confirms the entry by clicking Submit.
7. If the merchant and the buyer’s card are enrolled in the 3D Secure program, the payment will be authenticated with 3D Secure.
8. An authorization request is sent to the buyer’s bank, the issuer, in addition to internal fraud verification on the payment gateway.
9. In case of success, a summary page is presented to the buyer with a summary of transaction details.

   A button allowing to return to the shop is presented.

Figure 3. Transaction summary

In case of failure, a message is displayed. The buyer is informed of the payment request rejection. A button allowing to cancel and return to the shop is presented.

If you have configured a number of additional attempts that is higher than 0 in your Expert Back Office, the buyer will be able to make another attempt to finalize their payment. If he or she accepts, the payment process resumes at the stage of payment method selection.

Once the additional attempts have been used, the payment is permanently rejected.

Figure 4. Summary page in case of a failed transaction