The issuer identification number (IIN) is a unique six-digit code that identifies the issuing bank or other financial institution that issued a credit or debit card. It is used by merchants and payment processors to determine which bank issued the card and to route payments appropriately.

Format:

The IIN is typically formatted as the first six digits of the card number. For example, the IIN for a Mastercard card is 51, and the IIN for a Visa card is 4.

Examples:

• Mastercard card number: 5112 3412 1234 56
• Visa card number: 4123 4567 8901 234
• Discover card number: 312 345 678 901

Purpose:

• Routing payments: The IIN is used to route payments to the correct bank.
• Fraud detection: The IIN can be used to detect fraudulent transactions.
• Card type identification: The IIN can be used to identify the type of card (e.g., Mastercard, Visa, Discover).

Additional information:

• The IIN is assigned by the American National Standards Institute (ANSI).
• The IIN is also known as the Issuer Identification Number Scheme (IINS).
• The IIN is not a secret number, but it should be kept confidential.