① CVV2 is the number printed in the signature area of Visa/MasterCard card;

② 3 digits after the credit card number;

③ The last three digits we usually see on the back of a credit card are CVV 2；;

After the credit card is replaced, even if the card number is the same, the CVV2 code behind it will change. It is just like the ID card of a credit card, so it must be kept well.

⑤ You can find a sticker to stick it up to avoid being stolen by others when swiping the card.