What is the CID and WHERE is it?

The Customer Card ID Number (CID or CVV2) is a three or four digit number that is unique to each card.
This additional security feature is designed to protect you by helping to ensure the card is present during the purchase.
It is printed only on the card, never on any receipts or statements.
American Express Card Holders:   Visa, Mastercard, and Discover
The Card Identification # is the 4 digit, non-embossed number printed above your account number on the face of your card. This number is recorded as an additional security precaution.

Private Payment User? Please use the CID from your issued American Express Card.

If your AMEX account number does not have a plastic card associated with it, then you do not have a Card Identification #. In this case, you should enter the last 4 digits of your AMEX account number in the Card Identification # field in order for your transaction to be processed.
 
American Express Card Example
 
CVV2: A new Three-Digit Value
An important new security feature for card-not present transactions now appears on the back of most Visa cards. This new feature is a three-digit value which provides a cryptographic check of the information embossed on the card.

CVV2’s Location
The CVV2 three-digit value is printed on the signature panel on the back of Visa cards immediately following the Visa card account number.
 
CVV2 Example
The CVV2 value helps validate two things:
  • The Customer has a Visa card in his/her possession.
  • The Card account is legitimate.
CVV2 is printed only on the back of Visa cards--it is not contained in the magnetic stripe information, nor does it appear on sales receipts.