The cvv on card or the Card Verification number is a three or four digit number placed on the back side of the credit card. It is commonly demanded when a customer tries to purchase online and its function is to prove to the online merchant that you actually have the physical card, so it is devised to minimize the possibility of fraud. It should not be confused with the card pin code.
If the data from the magnetic band of a credit or debit card can be tracked dumper can withdraw any encrypted information out of the tracks and subsequently make a legit copy of the compromised card that can be used in brick and mortar stores to buy goods or even to withdraw money from an ATM machine if the pin code is also available.
CC dumps are illegal digital copies of the information contained on the magnetic track placed at the back of a valid credit card, which generally includes information such as card number and its expiration date. This data might be used to make an unauthorized copy of an active credit card in order to make purchases with it in fraudulent way or even for identity theft.