What is the code on the back of a credit card?

The code on the back of a credit card is a three-digit number known as a Card Security Code (CSC) or Card Verification Value (CVV), among other names. This code is on the back of credit cards because it helps to prevent fraudulent purchases from being made online or over the phone. You’ll need to provide it whenever you make a so-called “card not present” transaction – such as a purchase from an online merchant. A credit card’s security code is not always three digits long or on the back of your card, however. American Express cards are the exception – they have a four-digit security code on the front.

That’s the simple explanation, at least. But there are a few other important things you should know about your security code.

Here's some more info about the code on the back of your credit card:

• The CSC is also known as a Card Verification Code (CVC) or Card Verification Value (CVV). It is usually a 3- or 4-digit number printed on a credit card, not embossed like the card number.
• When you make a “card not present” purchase, either online or over the phone, you will have to provide the code. This confirms you are in possession of the card and the transaction is most likely legitimate.
• You don’t have to provide the code on the back (or front) of your credit card when you make purchases in person. The CSC is read when the card is swiped, dipped or tapped.
• The length and location of the security code on a credit card depends on the card’s network. On a Visa, Mastercard or Discover card, it is a three-digit number on the back of the card, to the right of the signature panel. With an American Express card, the code is four digits on the front of the card, above and to the right of the card number.
• The security code on a credit card is not the same as a card’s PIN. A PIN, which you might use to do a cash advance or verify an in-person purchase with some card readers, is not printed on your card. You generally have to request one by phone.

Remember, the code on the back (or front) of a credit card is a safety feature, so be sure to protect it. Never provide your code to anyone but a merchant when you’re paying them. And never send it in an e-mail, which is almost always an unsecured transmission.

If someone has access to your card number, expiration date, and security code, an online merchant would have no reason to suspect a purchase is fraudulent. The good news is that credit cards all give you a $0 fraud liability guarantee. As long as you report any unauthorized purchases to your card’s issuer, you won’t have to pay for them.

That's just another layer of security for your card. You don't need it to pay at the register or something, it's usually for online purchases.