3D Secure is a security protocol implemented globally by Visa and MasterCard to combat credit card fraud and improve the security of online transactions. A common form of credit card fraud occurs in restaurants and shops, where waiters or cashiers swipe your card in a card reader to capture the details, or take the card away and quickly write down the card details. They sometimes get paid to do this by crime syndicates, who then use your card details to make fraudulent purchases online.
Verified by Visa and MasterCard SecureCode will prevent the criminal from being able to use your card, even if the card has been swiped or stolen. It protects the merchant from charge backs relating to authentication disputes and provides the cardholder greater reassurance and security at every participating on-line store. This is done by adding an extra level of authentication during the transaction, which requires you to provide a password, phrase or pin number chosen by you, to prove that you are the cardholder.