When a new credit card arrives in the mail, you need to activate it by phone or online. Most cards also say to sign the card before using it. The signature is supposed to be for security reasons, but some people are not so sure. There are a few reasons why you should and should not sign the back of your credit card right away.
Credit card companies tell you to sign your card when it arrives. Without a signature, the card might not be valid. The signature activates the card, as well as gives merchants something to compare your signature to when you sign for a purchase. The theory is that if someone steals your card and uses it in a store, they likely cannot reproduce your signature, which is an indication to the merchant that the person making the purchase with your card might not be you.
Some people choose to write "See ID" in the signature space rather than sign the card. This is a tactic used to let merchants know that anytime the card is used, they should ask you for your ID, like a driver's license or other photo ID, to prove the card is yours. That way, if someone steals the card and tries to use it, they need to show a photo ID, and if the name or photo do not match, the merchant is not supposed to allow the purchase to go through.
Leave if Blank
Another option is to leave the signature line blank. When a merchant swipes your credit card, that merchant is supposed to check the back of your card for a signature. If there is no signature, they are supposed to ask you to sign the card, though many will simply ask to see your ID instead. The ID will prove whether or not the card is yours.
Cards with Photos
Another option to prevent credit card fraud for in-person purchases is to get a card with your photo on it. Many companies offer this option; you upload a photo to the company's website, and the photo is printed right on the card. That way, merchants can compare the photo to you in person. If the photo does not match, then the merchant should ask for additional ID to prove that you are indeed the cardholder.