As it appears on your credit card:
For your security, we use SSL encryption to send your credit card information to the credit card processor, and we do not
store your credit card information on our servers.
The Credit Card ID or Card Verification Value is often required to verify that you have the credit card in your physical possession.
It may appear in various places on your credit card.
On American Express cards, this is a 4 digit number on the front of your card.
On Visa, MasterCard and Discover cards, this is a 3 digit number that most likely appears on the back of your card near or on the signature box.