The technology that enables Face ID is some of the most advanced hardware and software that we’ve ever created. The TrueDepth camera captures accurate face data by projecting and analyzing over 30,000 invisible dots to create a depth map of your face and also captures an infrared image of your face. A portion of the neural engine of the A11, A12 Bionic, A12X Bionic, and A13 Bionic chip — protected within the Secure Enclave — transforms the depth map and infrared image into a mathematical representation and compares that representation to the enrolled facial data.

Face ID automatically adapts to changes in your appearance, such as wearing cosmetic makeup or growing facial hair. If there is a more significant change in your appearance, like shaving a full beard, Face ID confirms your identity by using your passcode before it updates your face data. Face ID is designed to work with hats, scarves, glasses, contact lenses, and many sunglasses. Furthermore, it's designed to work indoors, outdoors, and even in total darkness.

To start using Face ID, you need to first enroll your face. You may do this during the initial set up process, or at a later time by going to Settings > Face ID & Passcode. To unlock your device using Face ID, simply glance at it. Face ID requires that the TrueDepth camera sees your face, whether your device is lying on a surface or you're holding it in a natural position. The TrueDepth camera has a similar range of view as when you take a photo or make a FaceTime call with the front camera. Face ID works best when the device is arm’s length or less from your face (25-50 cm away from your face).

The TrueDepth camera is intelligently activated; for example, by tapping to wake your screen, from an incoming notification that wakes the screen, or by raising to wake your iPhone. Each time you unlock your device, the TrueDepth camera recognizes you by capturing accurate depth data and an infrared image. This information is matched against the stored mathematical representation to authenticate.