VISA networks and MASTERCARD finalized the 3D standard Secure to protect you during a purchase on internet against the fraudulent uses of your bank card.

So, when you make a payment on a retail website creating logos " Verified by Aimed " and "Mastercard Securecode", you seize your information contained on your bank card.
Then, you go etre to redirect towards the site of your bank on which it is asked to you to authenticate you to validate the payment of the purchase.
Your bank so verifies that you are the justifiable carrier of the card.
According to banks, this code can vary, he can be asked you your date of birth, your maiden name, or another code of authentification was passed on by SMS of the part your bank.
To parametrize or get back your 3D code Secure.
Click your bank for more information :

Banque Postale Société Générale Crédit Agricole Banque Populaire Crédit Lyonnais BNP Paribas Crédit Mutuel Caisse d'Epargne Groupama CIC