What your card number means?

Most national credit-card systems use ANSI Standard X4.13-1983.

• The first digit in your credit-card number signifies the system:
  • 3 - travel/entertainment cards (such as American Express and Diners Club)
  • 4 - Visa
  • 5 - MasterCard
  • 6 - Discover Card

• The structure of the card number varies by system. For example, American Express card numbers start with 37; Carte Blanche and Diners Club with 38.
• American Express -
  
• Digits three and four: Type and currency,
  
• Digits five through 11: The account number,
  
• Digits 12 through 14: The card number within the account
• Digit 15 is a check digit.
• Visa -
  
• Digits two through six are the bank number,
  
• Digits seven through 12 or seven through 15 are the account number
  
• Digit 13 or 16 is a check digit.
• MasterCard -
  
• Digits two and three, two through four, two through five or two through six are the bank number (depending on whether digit two is a 1, 2, 3 or other).
  
• The digits after the bank number up through digit 15 are the account number,
  
• Digit 16 is a check digit.