3D Secure is an additional step you can enable to happen every time a card transaction is made online. It enhances security measures for shoppers and vendors alike. When you turn on 3D Secure, you’ll be asked to validate every transaction with your PIN code.

3D stands for “three domains.” The first is the card issuer; second, the retailer receiving the payment; and third is the 3DS infrastructure platform that acts as a secure go-between for the consumer and the retailer.

When you make a payment for an online purchase, 3DS technology gauges if further safekeeping is needed to make sure that you are the rightful card owner. If so, you’ll be directed to a 3DS page and asked for a password or PIN.

Simultaneously, your bank generates a one-off PIN and sends it to your phone via SMS. This is the PIN you’ll need to enter before you can complete the transaction.

The process was developed by Visa and is now licensed to Mastercard, so most major card providers already use this technology. And just because 3D Secure is enabled doesn’t mean you’ll always have to enter a PIN—you’ll only have to complete this step if your bank notices a possible security issue.