What Do Credit Card Numbers Start With?
Explore the meaning behind credit card numbers. Learn how their unique structure identifies card networks and supports secure transactions.
Credit card numbers are unique identifiers that play a fundamental role in financial transactions. These sequences of digits follow a structured pattern designed to identify the card issuer, card type, and the cardholder’s account. This design is essential for ensuring the security and efficiency of daily transactions, allowing for seamless processing across various payment systems.
The Major Industry Identifier
The first digit of a credit card number is the Major Industry Identifier (MII). This digit categorizes the type of entity or industry that issued the card. For instance, ‘1’ or ‘2’ indicates airlines, while ‘3’ is associated with travel and entertainment, including American Express and Diners Club.
Banking and financial institutions use ‘4’ and ‘5’ for networks such as Visa and Mastercard. Digit ‘6’ represents merchandising and banking, where Discover cards are found. Other MIIs exist for industries like petroleum (‘7’) and healthcare or telecommunications (‘8’).
Identifying Card Networks
The initial digits of a credit card number identify the specific card network. Visa cards begin with ‘4’. Mastercard cards start with ‘5’, often within the range of ’51’ through ’55’, though newer numbers may also begin with ‘2’. American Express cards start with ‘3’, specifically ’34’ or ’37’, and are 15 digits long, unlike the more common 16-digit cards.
Discover cards start with ‘6’, including prefixes like ‘6011’, ‘644’ through ‘649’, and ’65’. Diners Club cards, often 14 digits, begin with a ‘3’ in ranges such as ‘300’ through ‘305’, ’36’, ’38’, or ’39’. JCB cards start with ’35’, particularly ‘3528’ or ‘3589’. These distinct starting digits allow payment systems to quickly route transactions to the correct network for authorization.
Understanding the Rest of the Number
The first six to eight digits of the card number, which include the MII, form the Issuer Identification Number (IIN), also referred to as the Bank Identification Number (BIN). This segment identifies the specific bank or financial institution that issued the card. Following the IIN, the Primary Account Number (PAN) is unique to the individual cardholder’s account. The final digit is a check digit, which validates the card number’s authenticity and detects errors. This digit is generated using an algorithm, such as the Luhn algorithm, which helps verify the accuracy of the entire number during a transaction.