A sign-in seal is a secret message or image that you create to help protect your Yahoo! account from phishing. Phishing — a play on the word "fishing" — is an attempt to steal your password and private account information.
Phishers create fake web sites that look like those of legitimate companies like Yahoo! to trick you into disclosing your user name and password. These pages often look identical to the real thing, so it can be hard to tell that you are on a phony, or "spoofed," site.
Creating a Yahoo! sign-in seal for your computer will help you ensure that you're on a legitimate Yahoo! sign-in page each time you use that computer to sign in to Yahoo!. Just look for the custom text or image you set up on the computer. If it's not there, you might have landed on a "spoofed" site.
Your Yahoo! sign-in seal is saved on the computer you created it on. If you use more than one computer or browser, you should create a sign-in seal for each one. So if you create a Yahoo! sign-in seal on your computer at work, we suggest you create one on your home computer, too.
Important: Don't create a Yahoo! sign-in seal on a computer you share with strangers, such as those in libraries, Internet cafes, and other public places.
Creating a sign-in seal is fast and easy: Once you do, look for it every time you sign in to make sure you're on a genuine Yahoo! site.
If your seal does not appear, beware: You could be on a fraudulent site, although there may be other reasons you're not seeing it.