What Your Credit Card Number Means

Did you ever wonder what those four groups of four numbers mean on the front of your credit card? Sure, it’s your account number, but is it more than just a random number? Yes. First, the sixteen numbers are grouped into fours just so that they are easier to read. It makes sense that four groups of four is easier than sixteen in a row. The first number means something all by itself. This is the Major Industry Identifier (MII), which indicates the type of institution that issued your card. I can see you going into your wallet or purse now to see what you have. A number that starts with a 1 or 2 was issued by an airline. A 3 indicates travel or entertainment. This could be a Diners Club Card or American Express branded card. 4 or 5. Banking or financial. A 4 is specific to Visa and Visa branded cards. A number 5 is specific to MasterCard and MasterCard branded cards. 6 is Merchandising and banking. Predominantly department stores and specialty store charge cards. 7 & 8 were reserved for oil companies and telecommunication companies. The next six numbers are the six digit Issuer Identifier Number, or IIN. This number relates specifically to the company that issued your card. So, Sears, or Bank of America, or Shell all have an individual six digit identifier. How the card issuer uses the identifier will vary. The first digits will tell the type of card or perhaps the issuing bank. Some credit card companies use the numbers to identify the country of origin for the credit card. That brings us up to seven numbers, so there are nine more. The next eight make up your account number. In certain cases the cardholders account will be these nine numbers plus some of the digits used for the IIN. Check it and see. The final number is a single digit checksum or check digit. This is a number that is produced by an algorithm to make sure that all of the other numbers make sense. It doesn’t need to make sense to you. So, the next time you try to use your credit or debit card to enter an account number, be sure to leave off the first six digits and the last digit. The other digits on your card are the expiration date and the Card Identification Number that for some inexplicable reason is called a CID. The expiration date is easily understandable. That’s the date when the card expires and no longer works. The CID is found on the signature line on the back of the card and is normally three digits. Credit card transactions where the merchant is unable to physically see the credit card in your possession (such as with payments over the Internet or by phone) sometimes require a little extra proof that you have the card in your possession. To get this proof they ask for the CID. The purpose of providing the CID is to let the merchant know that you have the credit card in your physical possession when you pay for a product or service. In that way, reading off or typing in the CID acts as a security precaution. Even if someone had your credit card number, they still would not know your CID. A thief who attempts to use your credit card number (perhaps off a receipt he or she found) would be unable to make purchases using your card at merchants that require the CID in order to complete a transaction. It's advisable to never provide your credit card’s Card Identification Number to any party that calls you making the request. However, it can be expected that a reputable retailer will ask for the information should you initiate the call and request to make a purchase over the phone or perform a similar transaction online. In these instances the information can and should be provided to facilitate the transaction.