Bank Identification Number (BIN)

For example, when you purchase something with your Visa card, the vendor and the payment processor receive a six- to nine-digit ID number. The first six digits identify the type of credit card (i.e., whether it's a MasterCard, Discover, Visa card or one from a department store) and the bank that issued the card.

When an electronic system validates a card transaction, part of the process is checking a database of BINs. (The American Bankers Association assigns and distributes BINs.) It keeps these BINs in a secure, nonpublic database. The configuration and data in the database can vary by country (for instance, BINs are only four digits in some countries).