To improve credit card security for online shopping, UK banks have introduced a security code - or "CV2" number on the back of every credit/debit card. This extra number provides an added level of security in addition to your card number and expiry date.
The security code number is the last THREE digits of the number found on the signature strip on the back of your card.
Please note: On American Express cards the security code is a FOUR digit number on the FRONT of the card.