Introduction
It's hard to find anyone over the age of 18 who doesn't own at least one credit card. Many even have multiple credit cards ranging from bank cards to department store account cards. Even with so many different cards numbers floating around in the market, credit card companies are still able to uniquely identify each individual card. This is done through credit card numbers.
First Digit
The first way that credit card numbers work is through their first digit. The first digit represents which system the card belongs to. A card that starts with the number three on it signifies a Diner's club or American Express card. Cards starting with the number four signify a Visa card, five a Master Card and six a Discover Card.
Bank Number
When it comes to the rest of the credit card numbers, most national credit card companies go by the 16 digit ANSI Standard X4.13-1983 system. In this system the next three to six numbers represent the bank number, signifying which bank the credit card is issued through.
Account Number
The next set of numbers (usually the next six to eight) signify the account number. Each person who has an account through the bank will be given a unique account number. The amount of numbers in the account will vary depending on the bank issuing the card. For example, banks that use Visa typically assign numbers 7 through 12 or sometimes 7 through 15 to the account number.
Check Digit
One of the most important numbers on the credit card is the check digit. A check digit is usually found towards the end of the credit card number, and is used as a way to validate that the credit card number is real. Check numbers use special math algorithms (such as MOD 10) that, when applied to the rest of the credit card numbers, total the check digit.
Magstripe
Credit card numbers can be manually typed into a credit card system, but in most cases they are scanned through credit card readers. To do this, the credit card number is implanted into a magnetic strip on the card called a magstripe. This magstripe holds all the personal information of the card holder, which is transmitted for billing when the magstripe is swiped through the credit card reader. Billing companies can then withdraw the money from your bank account or credit line by recognizing the bank identity and personal account number and using that information to locate and access your account.
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