Major Industry Identifier (MII) is a term used to classify the type of institution that issued a payment card.
The first digit of a credit card number is the Major Industry Identifier, which represents the category of the institution that issued the card.
The MII values and their corresponding categories are listed below:
| MII Value | Category Description |
|---|---|
| 0 | ISO / TC 68 and other industry assignments |
| 1 | Airlines |
| 2 | Airlines and other industry assignments |
| 3 | Travel and entertainment |
| 4 | Banking and finance |
| 5 | Banking and finance |
| 6 | Merchandising and banking |
| 7 | Petroleum |
| 8 | Telecommunications and other industry assignments |
| 9 | National assignment |
For example, American Express, Diner's Club, and Carte Blanche fall under the travel and entertainment category; VISA, MasterCard, and Discover fall under the banking and finance category; and SUN Oil and Exxon fall under the petroleum category.
Identifying the card brand from the first digit
In practice, the first digit quickly indicates which sector or scheme the card belongs to. For example, Visa cards start with 4, Mastercard cards generally start with 5 or 2, and American Express cards start with 3. National schemes such as Troy use ranges starting with 9.
Payment forms can display the scheme's logo and perform length validation based on the first digits of the card number. The Luhn algorithm is also used for validation; however, this algorithm only catches typing errors and does not prove that the card is genuine.
