CVV is an anti-fraud security feature to help verify that you are in possession of your credit card.

For Visa / Mastercard, the three-digit CVV number is printed on the signature panel on the back of the card immediately after the card's account number.

For American Express, the four-digit CVV number is printed on the front of the card above the card account number.

 
Visa / MastercardAmerican Express
A 3-digit number in reverse italics on the back of your credit cardA 4-digit number on the front, just above your credit card number