As you're probably aware, TouchID uses your fingerprint(s) as an alternative to your normal passcode when unlocking your iPhone. But that doesn't mean that you can forget about your passcode altogether - apart from anything else you'll need it every time you want to enter the TouchID settings panel.
Once you've got into these settings you can also tell your iPhone to use TouchID to authorize your purchases on iTunes or the App Store, which is a handy timesaver if you've got a strong-but-complicated password for your iTunes account.
Set up Touch ID
If your iPhone has TouchID then it will prompt you to scan your finger when you set the phone up for the first time. Don't forget, though, that you can add multiple fingerprints whenever you want. This is a good idea, as I've found that I prefer to use different fingers at different times. I use the thumb on my right hand when holding the iPhone, but I use a different finger - and sometimes a different hand - when I've got the iPhone sitting on a desk in front of me.
You can scan up to five fingers, which should be enough for most people, and you can also delete fingers as well. We've seen workarounds on the web that allow you to scan more than five fingers, but we wouldn't recommend doing that as it could muck up your iPhone's security settings.
Changing your iPhone passcode
Once you've set up TouchID it is possible to turn off your passcode altogether. But you should remember that the passcode isn't used just to unlock your iPhone. It also restricts access to many important settings on your iPhone, as well as passwords and even credit card details that you might have stored in Safari and other apps.
There's an option here to change your passcode if you want, and you can also turn off the 'simple' four-digit passcode and use a longer passcode that can contain numbers, letters and symbols too. And, if you scroll right down to the bottom of this panel, you'll find the 'Erase Data' option - the ultimate security option that deletes all data on the iPhone after 10 failed attempts at guessing the password.
One other thing to remember is that, even with TouchID activated, you'll still be asked to enter your passcode each time you restart your iPhone after being completely turned off, or if you haven't used your iPhone for 48 hours.
Decide what appears on the lock screen
This settings panel also includes a few options that aren't directly related to either TouchID or your passcode, but which do affect how the Lock screen works when your phone is still locked.
Sign up for CIO Asia eNewsletters.