Identify a credit card by number. . However, not all credit cards have the same sets of extra codes used to identify that the card is authentic. . . . . . The first 6 digits of a credit card number are known as the Issuer Identification Number (IIN), previously known as bank identification number (BIN). . . . If you are a merchant, every now and then a customer may place an order online or over the telephone and forget to tell you what kind of credit card she is using . These identify the inst... more