The purpose of signing on the back of the card is to ensure the cardholder’s safety when using the card. Please be sure to sign. It is optional to sign what you sign. Just remember how to sign. You signed the wrong one when making payments at the merchant. If so, the merchant may refuse to accept it. Of course, if your card has a transaction password set up, or it is a photo card, you can not sign it, but this will eliminate a layer of protection.

After signing, do not try to erase it in any way, otherwise the special paper in the signature area will peel off and the card will be invalid (it is very dangerous if the signature is so easy to modify, haha).