A code is printed on the Debit or Credit Card and is referred to as the Card Verification Value (CVV). It is a secure code and should never be shared with anyone.
For Visa, MasterCard and Diners, CVV is the final three digits of the number printed on the signature strip on the back of the card. CVV is optional for Maestro card.
It is also named as CVV2 or CVC in some banks across India.