The first digit of every credit card, debit, prepaid or gift card and also the first of six digits of the BIN (or IIN) number. §   0 — ISO/TC 68 and other industry assignments
§   1 — Airlines
§   2 — Airlines and other industry assignments
§   3 — Travel and entertainment (Amex, Carte Blanche, Diners Club)
§   4 — Banking and financial (Visa)
§   5 — Banking and financial (MasterCard)
§   6 — Merchandizing and banking (Discover)
§   7 — Petroleum
§   8 — Telecommunications, Healthcare or other industry assignments
§   9 — National assignment (followed by a 3 digit country code)
The last digit on the card is the Check Digit, for validation using an algorithm where all of the numbers are added up in specific combination. For more information, see Anatomy of a Credit Card number.

« Back to Glossary Index