3D Secure stands for Three Domain Secure - the payment industry's internet authentication standard which has been developed by the major card schemes. Visa has called their version of the scheme 'Verified by Visa' and MasterCard have called their equivalent initiative 'MasterCard SecureCode'. These are both collectively referred to as 3D Secure.
3D Secure authentication requires the cardholder to register their card to take advantage of this service. This is a onetime process which takes place on the card issuer's website and involves the cardholder answering several security questions to which only the card issuer and cardholder will know the answer. The cardholder selects a password and agrees on a secret phrase, which will be used by the card issuer during each online transaction.
3D Secure can be thought of as an online version of 'Chip and Pin' technology, whereby the cardholder has a personalised password registered with their card that is entered during the checkout process.
When you have entered your card details in our payment page, if supported by your card issuer, you will be either asked to enter your 3D secure password, or if not registered you will be offered the opportunity to register. If you do not enter the correct 3D secure information your payment will be declined.