Q: Where is the Card Security Identification Number?
A: For your protection, The Address Verification or Card Identification Number is the 3 to 4 numbers immediately following your credit card number. These numbers are used by your credit card company to help prevent fraud. Because the Card ID number is not printed on your receipts, it helps ensure that someone is not using your credit card information fraudulently.
American Express has 4 digits on front of card, Visa and MasterCard last 3 digits on back of card Note: The digits are printed on your card, rather then stamped in the plastic like the digits in your credit card number.