When a customer makes an online payment on a website that supports 3D Secure, the following steps occur:

1. The customer is directed to a 3D Secure page hosted by their card-issuing bank.
2. The bank may request a password, PIN, or a one-time password (OTP) sent via SMS to verify the cardholder’s identity.
3. If the authentication is successful, the transaction is completed.
4. If the authentication fails, the transaction is declined, and an error message is displayed.