The credit card verification value is a special security feature of your Visa, MasterCard, American Express, or Discover credit card. The verification value is not raised, so they are not scanned into standard credit card readers. In theory, these numbers are only visible to you. When you give your verification value to a merchant, you assist the merchant in verifying that the order is being placed by you, the card holder.
Flip
your card over and look at the signature box. You should see a special 3-digit code after your card number. This 3-digit code is your card verification value.
Your verification value is usually four digits printed on the front of your card after your card number.