If you are a card holder then you get a unique password from Visa. Your Verified by Visa password helps ensure that only you can use your Visa card number to buy online.
The image below represents how Verified by Visa protects you while shopping online.
Once your card is activated, your card number will be recognized whenever you purchase at participating online stores. You'll enter your password in the Verified by Visa window, your identity will be verified, and the transaction will be completed. In stores that are not yet participating in Verified by Visa, your Visa card will continue to work as usual.
When the consumer clicks "buy" at checkout, software installed on the merchant server recognizes registered Visa cards and the Verified by Visa screen automatically appears in the your browser. You simply enter your password and then the password is verified with Visa.
Read more about how it works from MasterCard »