When you flip your credit card over you will see a magnetic stripe. This magstripe is composed of very tiny bars of iron-based magnetic material encased in a plastic like film. It is the magnetic properties of the magstripe that allow it to store information. Each time you swipe your card through a credit card reader, sensors read the information within the magstripe.
The typical credit card comes with three tracks on the magstripe. All three tracks are only 0.110-inches wide. Currently most credit cards only use the first or second track. The first and third tracks are capable of handling the most data while the second track is less dense.
So what kind of information is stored on the first magstripe track? Your credit card issuer uses a proprietary format that only it can understand for some information (Format A), and a second format for information it shares during transactions (Format B). This track can only contain a total of 79 alpha numeric characters.
The following information is written on the card before you ever use your card in Format B.
- Your primary account number –This can be up to 19 characters
- Your country code
- Your name
- The expiration date of the card
- Additional discretionary data
- Longitudinal Redundancy Check (LRC)
The second track also contains your primary account number, country code, expiration date, discretionary data and LRC. It can only contain 40 numeric characters.
The third track may or may not be used by your credit card issuer. It also only allows the use of numeric characters, though it can store up to 107 characters.
Limited Information on the Magstripe
With such the magstripe allowing such a limited amount of information storage, those stories you may have heard about how your credit card history is being stored on that little black strip aren’t true. With most cards, the magstripe only contains the information need to initiate and complete transactions.
But beware there can be additional personal information stored on some cards. For some unexplainable reason, some cards have been known to include full social security numbers. This places you in an extremely vulnerable position if your card is ever lost or stolen. It makes identity theft all that easier.
Importance of Keeping Your Card Secure
Technology is out there to duplicate magstripes. A quick swipe through a miniature magnetic-stripe reading device, and a copy of your card can be manufactured from the stolen information. “Skimming” is something to keep your eye out for. Never let your credit card or debit card out of your sight. Restaurants are the site of more skimming operations than anywhere else. Why? Because it’s standard practice to lay the card on a tray and let the waitress take care of paying the bill for you.
Even when you always pay for your purchases personally, you need to remain on your guard. If you see your card being swiped twice, don’t be afraid to express your suspicion and draw attention to the fact. The second swipe could be to capture your information.
Outside Data Collection
Just because there are limitations on how much data a card can contain in the magstripe doesn’t mean that there aren’t data bases gathering information connected to your credit card use. Every time you swipe your card, information related to the specific transaction is transferred to multiple data centers. The merchant is going to save an electronic version of the transaction. Your credit card issuer is going to save the data from your transaction. And the credit reporting agencies will also be notified that you have incurred a new debt according to some sources.