If you are a credit cardholder, you probably see the stripe of black tape at the back of your credit card. Do you know what this stripe of black tape is for?

The stripe of black tape at the back of your credit card is called the 'magnetic stripe' or 'magstripe' in short. This stripe is made up of millions of tiny iron based material embedded in a plastic film.

The stripe is used by credit card companies to store your personal details, card details and security information. The stripe works like a magnetic tape cassette where you can record and overwrite data in it. However the stripe of a credit card is more powerful than that of the cassette. It is a three tracks stripe. Most credit cards only use two of the three tracks.

There are two types of magnetic stripes. One is hi-coercivity and the other is low-coercivity. Both types of coercivities are acceptable and can be used on the cards. The high coercivity magnetic stripe tends to be of higher quality and the data could be protected better and the colour is normally darker.

Because the stripe is magnetic based, it is very sensitive to heat and any objects with magnetic field. It is not advisable to put your credit card under the sun, near to a telephone or against another card magnetic stripe. Although the occurrence of the stripe data corruption seldom happen, it is better to avoid it if you can.

In the event that your credit card's magnetic stripe faulty, the problem could be any one or a combination of the following reasons:

1. The stripe is dirty or scratched. Such incidence it quite common. You just have to clean the magnetic stripe with a clean dry cloth. If it does not work, then you got no other alternative but to replace it.

2. The data in the stripe is corrupted or damaged. Such occurrence usually happened when your credit card is subjected to heat like putting under the sun or placed near to a strong magnetic field objects like telephone or television, etc.

3. The portion of the plastic card with the stripe is damaged or broken causing the magnetic stripe to be uneven or unreadable.

Data embedded in the magnetic stripe of a credit card

The most common data embedded in the stripe of a credit card are usually the cardholder number, cardholder name, company name if it is a corporate card, expiry date and a security code or usually refer as card validation code 1 or CVC 1. There is other further information that you can embed into the magnetic stripe but they are not as important as the earlier.

All the data embedded in the stripes are encrypted so the data are not visible. Unless you have the password to decrypt the encryption, you will not be able view any data in the stripe. This is one of the security measure used to deter fraud.

Other than the information in the magnetic stripe of the credit card, the rest of the information that are visible in front of the card are card number, cardholder name, expiry date, member since date and company name if it is a corporate card. All these information are either embossed or thermal printed on the front portion of the card.

At the back of the card, where you see a stripe of black magnetic stripe, there is a signature panel and some numbers (19 digits, 7 digits or 3 digits) indented in it or near it. The last three digits of the indented numbers are the card validation code 2 or commonly refer as CVC 2. The usage of this CVC 2 is usually used for identification or for non face to face purchases like internet, mail order or telephone order.

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