Issuer Identification Numbers (IIN)

An Issuer Identification Number (IIN), also known as an Issuer Identification Code (IID), is a unique number that identifies a financial institution that issues payment cards, such as credit cards and debit cards. The IIN is typically a 15-digit number, and it is used to identify the card issuer in the cardholder's bank records. The IIN is also used to validate the card number when it is used to make a purchase.

The IIN is typically located on the front of the card, in the upper-right corner. It is a 15-digit number, and it is usually preceded by the card brand's identification number (such as 4 for Visa, 5 for MasterCard, and 3 for American Express). The IIN is also sometimes located on the back of the card, in the signature panel.

The IIN is used by financial institutions to identify the card issuer in the cardholder's bank records. When a cardholder makes a purchase, the merchant's point-of-sale system sends the card number to the card issuer's bank. The bank uses the IIN to identify the card issuer, and it then validates the card number to ensure that it is valid.

The IIN is also used to validate the card number when it is used to make a purchase online. When a cardholder enters their card number into an online form, the merchant's website sends the card number to the card issuer's bank. The bank uses the IIN to identify the card issuer, and it then validates the card number to ensure that it is valid.

The IIN is an important security feature that helps to protect cardholders from fraud. By using the IIN, financial institutions can ensure that only valid cards are used to make purchases.