What is a Security Code?
The card security code is a three-digit number (four-digit on American Express) printed on your credit card. This number is not embossed on the card and hence not printed on receipts - making it difficult for anyone other than the genuine cardholder to know it and to use it.
You will find this three-digit security code printed at the top of the signature strip on the reverse side of Visa, MasterCard and Discover Card credit cards.
You will find this four-digit security code on the front of American Express cards, above the account number.