American Express 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.

Q: What is this and why do I have to do it? A: Due to the amount of credit card fraud over the internet, banks will soon REQUIRE this information to process credit card orders online - you can expect to see it used everywhere in the very near future; we just want to get a head start on it. Your benefit is that it prevents any fraudulent charges using your credit card, i.e. no one can pick up an old receipt of yours and use that info to fraudulently use your credit card. Thanks for your cooperation.