Credit card number

The numbers found on credit cards have a certain amount of internal structure, and share a common numbering scheme. Credit card numbers are a special case of ISO 7812 numbers.

An ISO 7812 contains a single-digit major industry identifier (MII), a six-digit issuer identifier number (IIN), an account number, and a single digit checksum using the Luhn algorithm.

The major industry identifier is considered to be part of the issuer identifier number.

The card number's prefix is the sequence of digits at the beginning of the number that determine the credit card network to which the number belongs. The first 6 digits of the credit card number are known as the Bank Identification Number (BIN). These identify the institution that issued the card to the card holder. The rest of the number is allocated by the issuer. The card number's length is its number of digits.

The prefixes and lengths for the most common card types are:

On November 8, 2004, MasterCard and Diner's Club formed an alliance. Cards issued in Canada and the USA start with 55 and are treated as MasterCards worldwide. International cards use the 36 prefix and are treated as MasterCards in Canada and the US, but are treated as Diner's Club cards elsewhere. Diner's Club International's website makes no reference to old 38 prefix numbers, and they can be presumed reissued under the 55 or 36 BIN prefix.

Effective October 1, 2006, Discover will now be using the entire 65 prefix, not just 650. Also, similar to the MasterCard/Diner's agreement, China Union Pay cards are now treated as Discover cards and accepted on the Discover network.

A search on VISA's website results in many references to card numbers being 16 digits long. However, searching for references to 13-digit cards will turn up no results. It might be presumed that 13-digit cards no longer exist and have been reissued as 16-digit cards, however old accounts may still use these numbers.

Switch will continue to exist until mid 2007, after that it will branded as Maestro. Maestro is now VISA Electron's main competitor in the European debit card market.

Solo can be used outside of Britain if the card displays Maestro.