bank card number, also known as a primary account number (PAN), is a series of digits that uniquely identifies a bank card and the associated account. It is usually 16 digits long, but may be 13 or 19 digits long. Here's a breakdown of the card number structure: **Card Number Structure:** 1. **Primary Industry Identifier (MII):** The first two digits (1-2) indicate the card type: * 34 or 37: American Express* 60-65: Discover* 5018-5038 or 6304: Maestro* 51-55: MasterCard* 40, 41, 42, 43, 44, 45, 46, 47, 48, or 49: Visa 2. **Issuer Identification Number (IIN):** The first 6 digits (1-6) indicate the issuing bank: * American Express: 34 or 37, followed by 4 digits * MasterCard: 51-55, followed by 4 digits * Visa: 4, followed by 5 digits 3. **Account Number:** The middle digits (7-12) are the account number: * This portion is the unique identifier assigned by the bank to the account 4. **Verification Digit:** The last digit (16) is the check digit: * This digit is calculated using the Luhn algorithm to verify the validity of the card number **Example:** Assume a Visa card number as follows: `4532015112830366` * MII: `4` (Visa) * Institutional Identification Number (IIN): `4532` (Bank of America) * Account Number: `0151128` (Unique identifier for the associated account) * Checksum: `6` (Check digit) Note that there may be other encoded elements in the card number as well, such as: * **Product Code:** Indicates the card type (e.g., rewards card, credit card) * **Owner Number:** An additional security feature that helps verify the card owner Keep in mind that the card number structure can vary depending on the card type and the issuing bank. Additionally, the checksum is calculated using the Luhn algorithm, which helps verify the validity of the card number. Do you have any additional questions or would like more information?