Credit Card Security Codes Due to the amount of credit card fraud over the internet, banks increasingly require this information to process credit card orders online. 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. 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.