CSC is an important security feature for credit card transactions on the Internet and over the phone. "CSC" stands for "Card Security Code".
The CSC number enhances fraud protection and helps to validate two things
The customer has the credit card in their possession.
The credit card number is legitimate.
By helping to prevent credit card fraud, the CSC number keeps costs down for everyone.
Visa & Mastercard
It is the three-digit number printed in the signature space on the back of most credit cards, such as Visa and Mastercard cards. The CSC number is always the last group of numbers in the signature space on the back of the card. It is not part of your regular credit card number.
American Express
It is a four-digit number on the front of American Express cards. It is printed (flat), not embossed like the card number.
Canada
International