Verified by Visa
Verified by Visa adds an extra layer of security to make it harder for someone else to use your Visa card to shop online in the unfortunate event your Visa card or account number is lost or stolen. Each time your Visa credit or debit card is presented to make an online purchase at a participating merchant, know that Verified by Visa is working to make sure it is you that is attempting to make that purchase and not someone else. There is no special software to install. You will continue to shop as usual, and your enrolled Visa card number will be automatically recognized at checkout.
Excerpt from http://usa.visa.com/personal/security/vbv/index.html
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