Credit card,Debit card, ATM Card..etc., whatever the type of card all these cards became part of our body.All these cards are almost physically same.
All the content written on the credit card are visible except the data inside the magnetic strip placed at the top of the reverse side of the card.
Do you know whats inside this magnetic strip?
This magnetic strip containes three tracks for storing data.
1. first track contains information about primary account number, user name, country code, card expairy date and 79 characters of discretionary data,all mixed in with separators and other characters, all this data is magnetically encoded.
2. Second track also contains the same information of the first track with 40 characters of discretionary data and separators
3. Third track is of both read and write. No standard format is defined ,data on this track may vary with the bank,it may have the data like PIN,Currency type..etc,
What actually happens when you swip your card at ATM or Store?
When your card is swiped through an electronic card reader at ATM or the checkout counter in a store , the reader will usually use its built-in modem to dial the number of a company that handles credit authentication requests.This company checks the information from the electronic card reader for a valid card number and expiration date, the card's spending and usage limits and the store identification. After all the data checks out, the purchase/transaction is approved.
If the magnetic strip on the back of your card becomes scratched, dirty or demagnetized, the card may not work properly and you will have to get a new one.