Also known as Mastercard Identity Check, 3D Secure is a free and automatic online security service. It gives you an extra level of security and helps to guard your credit card against unauthorised use online.
When you make a purchase in a shop using your credit card, you're asked to enter a PIN number to validate the transaction. 3D Secure allows you to validate transactions you make over the internet in a similar way.
Depending on the nature of the transaction, you may occasionally receive a text message to your mobile phone with a one-time passcode. You will have to enter that passcode to complete your payment online.
A mobile phone is required to receive a text message with your one-time passcode. You can check your account has the right mobile number in the Settings menu of your online account.
Find out more about 3D Secure Terms of Use .