The Card Identification Number (CID) is a short number that appears on your credit card apart from the actual credit card number. It is not contained in the magnetic stripe information and is therefore not printed on sales receipts. For VISA, MasterCard or Discover Cards, it is a 3-digit code located on the back near the signature area. For American Express cards, it is a 4-digit code that is usually embossed on the front of the card. It is one of two security features of the CVV.