This test URL will show you why quicker than I can explain it in words. Please try it and come back. If you’re using autocomplete to, for instance, sign up for an email newsletter, you might have just provided that website with your full address and/or (even worse) your credit card details too. It’s as simple as adding the fields to the form and hiding them from the user…

- Joost de Valk,

Its a fun test, seriously, go to the test URL.

The Autocomplete feature is a known risk but still often used, worse is the Chrome’s Insane Password Security Strategy. Basically, any time you have a browser store your information, especially Chrome, its a risk. 

OS X’s keychain presents a risk but at least the user has to have access to the computer’s admin password to root around in the keychain stored passwords.