Face ID Authenticates You Using the TrueDepth Camera
Face ID can be used to unlock your iPhone or iPad. Using the TrueDepth camera, Face ID determines whether the person looking at an iPhone or iPad is the enrolled user. Other uses of Face ID include making payments with Apple Pay, making purchases within the App Store, and authenticating within apps.
Face ID data — including mathematical representations of your face — is encrypted and protected with a key available only to the Secure Enclave. This data will be refined and updated as you use Face ID to improve your experience, including when you successfully authenticate. Face ID will also update this data when it detects a close match but a passcode is subsequently entered to unlock the device.
Face ID data does not leave your device, and is never backed up to iCloud or anywhere else.
You Have Control Over Face ID
If you choose to enroll in Face ID, you can control how it is used or disable it at any time. For example, if you don’t want to use Face ID to unlock your iPhone or iPad, go to Settings > Face ID & Passcode, enter your passcode, then tap to turn off iPhone Unlock or iPad Unlock. To disable Face ID, go to Settings > Face ID & Passcode, enter your passcode, then tap Reset Face ID. Doing so will delete Face ID data, including mathematical representations of your face, from your device. If you choose to erase or reset your device using Find My or by erasing all content and settings, all Face ID data will be deleted.
Face ID and Apps
Within supported apps, you can enable Face ID for authentication. Apps are notified only as to whether the authentication is successful. Apps can’t access Face ID data associated with the enrolled face.
Other Uses of the TrueDepth Camera
Even if you don’t enroll in Face ID, the TrueDepth camera intelligently activates to support attention aware features, like dimming the display if you are not looking at your iPhone or iPad or lowering the volume of alerts if you are looking at your device. For example, when you are using Safari, your device will check to determine if you are looking at your device and turn the screen off if you aren’t.
If you don’t want to use these features, you can go to Settings > Face ID & Passcode, enter your passcode, then tap to turn off Attention Aware Features.