A “bank identification number” or “BIN” is the first 6-digits of an account number used by a prepaid debit card issuer to identify their institution. Different card networks use different BIN numbers. For example, the American Express account number range begins with “3”, the Visa account number range begins with “4”, the MasterCard account number range begins with “5” and the Discover account number range begins with a “6”.
As a specific example, one of the BINs used to identify MetaBank‘s prepaid debit Visa cards is: “479347” (where the “4” shows the card is a Visa card, and the full six digits show that the card is issued by MetaBank).
Each Bank typically issues cards under more than one “BIN”. For example, MetaBank also issues Visa cards with the following bank identification number: “432732” (the “4” again indicates that the card is a Visa card).
MasterCard (and American Express, as well as other issuers) use similar numbers. For example, the BIN “533248” identifies a card as being issued by Comerica Bank, and that it is for a prepaid Mastercard program.