If you didn't configure Touch ID during the setup process you can do it later by following these steps:
Tap Settings > Touch ID & Passcode > Input your passcode
Tap Add A Fingerprint
Press one finger to the Home Button and hold it there until the iPhone or iPad vibrates.
Continue to tap the Home button, slightly changing the angle of your finger each time
Each time you tap the finger to the Home Button the fingerprint will get a little more detailed. Do not press the Home Button, you only need to gently push your finger against it.
How to add more fingers to Touch ID
You can add up to five different digits to Touch ID, wish to allow another family member to unlock your iPhone. To add more fingers simply tap the 'Add Finger' option within the Touch ID settings.
If you would like a family member to be able to unlock your iPhone you can use this process, too, to register one of their digits.
How to use Touch ID to unlock an iPhone and iPad
You use Touch ID to unlock your iPhone every time you wake it up from sleep. There are two ways to use it:
Press the Home button to wake up the iPhone or iPad, then place your finger on the Home button to unlock it
Press the Sleep/Wake button to wake up the iPhone or iPad, then hold your finger on the Home button to unlock it
After two failed attempts you'll be given the option to enter your passcode and after five failed attempts you'll need to enter your passcode to unlock your phone or tablet.
How to use Touch ID to make App Store purchases
Touch ID can also be used to make App Store purchases. To do this you need to ensure that Touch ID is setup to work with the App Store.
Tap Settings > Touch ID & Passcode
Tap iTunes & App Store to set it on (green).
When you next make a purchase you'll see a Scan Fingerprint option. You can now make purchases on the App Store with just a touch of your finger.
Will I need to ever use a passcode?
There are certain instances where you'll need to use a passcode, where Touch ID is not sufficient to unlock your phone or for you to do certain tasks. For example, you'll need a passcode if your device hasn't been unlocked for six days or if it hasn't been unlocked through Touch ID in the last eight hours.
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