The card security code (CSC), also known as the Card Verification Value (CVV) is a 3- or 4-digit
number associated with your credit card, printed only on the card and
not on statements or charge slips.
This has been implemented by the credit card companies as a type of authentication of the person using a card number to make an online purchase.
The theory: physical possession of the card is needed since the code is only on the plastic card. A hacker that has stolen a card number electronically won't be able to make purchases since they don't have the physical card with its code.
If you have physical possession of the card, then presumably you are in fact an authorized user of the card.
Giving the CSC to a merchant for an online sale to prove you have the card in your hand is the intended use of this security feature.
On most Visa and MasterCards, the CSC is usually
printed on the back of the card on the signature panel. On American Express
cards, it is printed on the face of the card.
To purchase products via Teracom's online sales,
you must enter this code (if your card has one) in the appropriate place
on the order form. If your card does have a CSC and you do not enter it
correctly, your purchase will be declined.
If your purchase is declined, please check your
email - you will receive a message explaining why. "CSCDECLINED"
means your card does have a CSC, and you have not entered it correctly. Please see below for help if you have problems.