As of 2014, credit and debit cards in the United States usually contain a prominently displayed 16-digit number. In addition to a unique card number, cards contain the bank's logo, the owner's name and the card's expiration date.
For most debit cards, the first digit of the 16-digit number identifies the card type, such as Visa or Mastercard. Subsequent numbers identify the bank and the account number. A check digit allows for validation testing and is included at or near the end of the card number.
Exceptions to the rule that card numbers are 16-digits in length do exist. American Express employs 15-digit numbers, while department stores and gas stations issue credit and debit cards with numbers that vary in length.