The Card Identification Number (Card ID) is required for all transactions with American Express, Discover, Visa and MasterCard. The Card ID is an added security feature used by your credit card company to protect you against online fraud. Because the Card ID number is not printed on your receipts, it helps to ensure that someone is not using your credit card information fraudulently.
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American Express 4 digits on front of card |
Visa, Discover and Mastercard last 3 digits on back of card |
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| The digits are printed on your card, rather then engraved on the plastic like the digits of your credit card number. |