Key takeaways. Credit card security codes are three-digit codes on the back of your card (four-digits on the front if you have an American Express card) used to verify that have the physical card.

A credit card security code is a three- or four-digit number designed to prevent fraudulent transactions. You might hear this code referred to as the Card Verification Value (CVV).

Your credit card's security code is a three- or four-digit number that helps protect you against credit card fraud. Learn how to find it and why it's important.