There's plenty of varied logic when it comes to signing the back of credit cards — some cardholders simply provide a signature, some sign but include a note to "See ID" and some write see ID in place of a signature. Your credit card agreement tells you that not singing the card is in violation of that agreement, and VISA's merchant guidelines say that a cardholder with see ID in place of a signature should be asked to sign her card on the spot [1].

Whatever signing (or not) practices we've adopted, we've made a reasoned choice based on what we believe to be most secure. What has been your card signing habit?

Source [2]