Most of us are curious by nature. So if you’ve been lying awake at night wondering what your 16-digit credit card number means, it’s your lucky day.
I’m going to pull the curtain back and show you not only what the numbers stand for, but also how they’re designed to detect an invalid credit card account number. I know the suspense is killing you, so let’s go.
Decode your credit card number
There are standards for account numbers, and this falls under the purview of the International Organization for Standardization. ISO is an independent international non-governmental organization.
So, credit card, which typically have between 13 and 16 account numbers, aren’t just random. Each digit conveys identifying information about the credit card, and the assigned numbers must follow the guidelines set by ISO.
However, there is some variation in how the standards are applied, and you’ll see what I mean when we get to the second set of numbers.
– The first number.
– Numbers 2 to 6.
– Numbers 7 to 15 (or more).
– The last digit.
The first number
This number is called MII, or Industry Principal Identifier, and it specifies the card’s network and industry. If your card starts with 3, your card uses the American Express network. Visa starts with 4, Mastercard is 5, and Discover is 6.
Other numbers are used to identify the industry. For example, 1 and 2 are used for the airline industry. The number 3 represents travel and entertainment, so it makes sense that 3 also indicates that it is an American Express card. (AmEx cards focus largely on travel.)
Here is a full list of MII numbers:
2. Airline and other industry missions.
3. Travel and entertainment.
4. Banking and finance.
5. Banking and finance.
6. Merchandising and banking.
8. Telecommunications and other industry missions.
9. Open for assignment.
Numbers 2 to 6
This group of numbers is called the issuer identification number. Usually, these numbers identify the company or institution that issued the credit card.
But note that different credit cards may have slightly different numbering systems. For example, Visa uses the second to sixth digits for the bank number. But American Express uses the third and fourth digits to identify the type of card and the currency used.
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Numbers 7 to 15 (or more, depending on the length of the account number)
These numbers are linked to the cardholder’s account. The numbers in this group are unique to a transmitter and help route information to the correct channels.
The last digit
The account number van has an important role. It’s called the check digit, and it’s designed to ensure that all account numbers represent a valid credit card number.
Payment processors use a checksum formula called the Luhn algorithm. It was invented by Hans Peter Luhn of IBM. It is used to determine if credit card numbers have a logical pattern. If the numbers do not work with the algorithm, it is not a valid credit card number.
Where is the security code on a credit card?
This is a three or four digit number, often referred to as the CVV, or card verification value. The location of the CVV depends on the network payment processor used.
– Visa, Mastercard and Discover: These networks have a three-digit CVV, and it is located on the back of the card.
– American Express: This network has a four-digit CVV, and you can find it on the front of the card.
The CVV is designed to increase security, as you will likely need to have the card in hand to know this code number. For example, if someone has stolen your credit card number and tried to buy something online, unless the thief knows your CVV, that person will not be able to complete the purchase.
This code also comes into play when you order pizza over the phone. You give the credit card number, and the restaurant clerk asks for the expiration date and CVV. It’s easy to answer, of course, if you look at the actual credit card.
[Read: Best Cash Back Credit Cards.]
It is by no means foolproof. It is possible that a thief has your physical card and has access to the CVV. But the security code provides another layer of security against certain types of fraud. In particular, he fights what is called ” missing card fraud, “or CNP fraud, which can occur online and over the phone.
So be sure to keep your CVV number. And when you share it, make sure you’re on a secure website or on a phone call you initiated.