Card verification value (CVV) is a combination of features used in credit, debit and automated teller machine (ATM) cards for the purpose of establishing the owner's identity and minimizing the risk of fraud. The CVV is also known as the card verification code (CVC) or card security code (CSC).
On a typical credit card, there are two components to the CVV. The first code is recorded by the card issuer in a magnetic stripe that runs lengthwise along the back of the card. This stripe resembles magnetic tape and can contain a large amount of data. The code is recovered by sliding the card through a magnetic stripe reader that picks up the binary data in a manner similar to the way a tape drive works. The second code is a multi-digit numeral printed flat on the card, separate from the longer, embossed account numeral. On a VISA, MasterCard or Discover Card, the printed CVV contains three digits and is located on the back near the signature area. On an American Express card, it contains four digits and is located on the front near the embossed account numeral.
When properly used, the CVV is highly effective against some forms of fraud. For example, if the data in the magnetic stripe is changed, a stripe reader will indicate a "damaged card" error. The flat-printed CVV is (or should be) routinely required for telephone or Internet-based purchases because it implies that the person placing the order has physical possession of the card. Some merchants check the flat-printed CVV even when transactions are conducted in person.
CVV technology cannot protect against all forms of fraud. If a card is stolen or the legitimate user is tricked into divulging vital account information to a fraudulent merchant, unauthorized charges against the account can result. A common method of stealing credit card data is phishing, in which a criminal sends out legitimate-looking Email in an attempt to gather personal and financial information from recipients. Once the criminal has possession of the CVV in addition to personal data from a victim, widespread fraud against that victim, including identity theft, can occur.