What is Apple Face ID? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.
Answer by Brian Roemmele, Founder + Editor at Read Multiplex, on Quora:
The Next Generation Of Authentication
As of September 12th, 2017, Apple Face ID is the new replacement to TouchID. Face ID is enabled by the TrueDepth camera and is simple to set up. It projects and analyzes more than 30,000 invisible dots to create a precise depth map of your face. Face ID works with iPhone X and unlocks only when you’re looking at it. It’s designed to resist spoofing by photos or masks. Your facial map is encrypted and protected by the Secure Enclave. And authentication happens instantly on the device, not in the cloud.
Face ID uses the A11 Bionic chip for the machine learning to recognize changes in your appearance. You can put on glasses, wear a hat, grow a beard. Even wild makeup will not fool Face ID, it will know you. Your friends might not recognize you, but iPhone X will.
Gaze And Gaze Shift
It is estimated that the accuracy of Face ID will be 1 in 1,000,000 when compared to the 1 in 50,000 of TouchID fingerprints alone. The TrueDepth camera uses 30,000 infrared dots harmlessly projected onto your face for depth mapping. The Infrared camera reads back these features and others below the skin's unique characteristics to create a secure biometric image of your face. The front side Flood Illuminator assists in creating normalized lighting for any condition, light or dark.
The infrared front facing camera will read the structure below the skin and the micro moments to confirm that a live subject and not an image is activating or unlocking the iPhone. For additional security, Face ID is attention aware, meaning it unlocks your iPhone X only when you look toward the device with your eyes open. That means Face ID can also reveal notifications and messages, keep the screen lit when you’re reading, or lower the volume of an alarm or ringer.
This technology has been available for quite some time  and was a part of the work done by PrimeSense, a company Apple acquired. Face ID will activate the iPhone in less than three milliseconds under most lighting conditions. The AI will decide when your gaze shifts and will lock the iPhone.
The setup for Face ID is simple; the user sees the video motion of the head and duplicates this with an outer ring indicator.
The gaze and the gaze shift will allow for a number of unique attributes to an app. At some point Apple may open a Face ID Kit API development tool allowing gaze to have in impact on the modality of the apps.
There is also a very good chance that technology gained by the 2016 acquisition of Emotient  may be used to gauge the emotional state of the user. This can aid in detection of a number of potential issues. It will aid in screening for static images as it would be impossible to simulate easily the transient movement of the forty-three muscles that control facial expression and the emotional intent.
Security And Speed
In 2013 I wrote extensively about TouchID . I said at the time:
Steve Jobs hated logins and passwords, and he was going to do something about it.
It was the late winter of 2007 and while many of us were just starting to get used to the iPhone and all the ways it was changing the world, Steve Jobs was already planning a completely new paradigm for a future iPhone release. Although Steve loved the “Slide To Unlock” feature, he knew that the steps involved and the time it took to unlock the screen when a passcode is being used was unacceptable. Steve predicted that as the iPhone became more indispensable and formed the center of our lives, it would be used perhaps hundreds of times per day, not just as a phone, but as our primary connected computer. Additionally, early data from iPhone users proved that only a very small percentage even bother using a passcode, that included Steve.
Steve and Apple engineers went about crafting a way to solve this problem and along the way they discovered that there could be a lot more use cases this new system could address. By September 9th, 2008, Apple began to file one of the first few patents addressing this technology.
Your fingerprint, all of your credentials
Steve and the team were forming one of the early foundational premises for the Touch ID: to secure what will become your most important device and to elegantly open the phone with just a tap of a finger. However, it became very clear that this level of security could be extended to a wide number of uses.
This premise, security and fast access, has driven Apple to continue to invent and build more advanced systems to Face ID today. Apple acquired RealFace in February 19, 2017 . The Israeli startup was a cybersecurity and machine learning firm specializing in facial recognition technology formed in 2014 for an estimated $2 million or somewhat more. Most of the technology in Face ID comes from RealFace with some technology from Prime Sense. On November 24, 2013, Apple purchased PrimeSense for $360 million and it also forms the foundation technology of ARKit.
New Face ID Based Apple Pay
Face ID with Apple Pay and Apple Pay Cash will fundamentally change how you pay. New streamlining and sounds guide the experience. Apple Pay will be invoked by a double press of the “side button”, the former “lock/power button”, showing a new wallet arrangement.
Apple Pay + Face ID will work on iPhone X about 50% faster than TouchID. New pay confirmation signals including sound and modified haptics will notify a completed Apple Pay + Face ID transaction.
The Face ID Icon
Face ID will have a simple setup process that uses this iconography and video to instruct facial position angles. This video will show you how to move your face during the initial setup of Face ID. Apple has had a long lineage of “faces” starting from the very first Apple Macintosh icon from 1984 designed by the amazing Susan Kare. This history spans to System 8 Finder in 1997, up to the current version of Mac OS and now on to Face ID.
Face ID Changes Everything
I also suspect that we will see Face ID used with a new version of HomePod for authentication at a distance. I wrote about this prospect in February, 2017  and tied the Apple acquisition ultimately to a Voice First system that has become HomePod. In my view, Apple wanted to release this technology first on iPhone and later on other systems like a new version of HomePod with a camera and display screen.
Face ID will radically change everything we thought we knew about authentication. It will change the way we use apps and payments. Face ID alone will become a central selling point for the next iPhones. Our faces have been our unique identity from the dawn of time, today with Face ID it moves into the world of AI, once again our face will be our ID.