What is a credit card CVV number?

A CVV number on a credit or debit card is a three or four-digit number printed on the back of the card used to verify that the user has physical possession of the card when making purchases, according to CVV Number. These numbers are also called card security codes.

MasterCard and Visa issued cards contain three-digit codes printed on the rear of the cards, while American Express cards use a four-digit code located on the front, states CVV Number. The purpose of the CVV number is to prevent fraudulent usage of the credit or debit account by those who have gained access to the card number without the actual card.