Apple's Face ID is a facial-recognition technology that launched on the iPhone X in 2017. The technology replaces Apple's Touch ID fingerprint scanning system for the company's latest iPhones, including the iPhone 11, 11 Pro and 11 Pro Max and it will likely be found on future iPhones too.

Face ID uses a "TrueDepth camera system", which consists of sensors, cameras, and a dot projector at the top of the iPhone display in the notch to create a detailed 3D map of your face. Every time you look at your phone, the system will conduct a secure authentication check, enabling your device to be unlocked or your payment to be authorised quickly and intuitively if it recognises you.

Here's how Face ID works.

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How does Face ID work?

TrueDepth camera system

Each time you glance at your iPhone X (or newer), the TrueDepth camera system will detect your face with a flood illuminator, even in the dark.

An infrared camera will then take an image, and a dot projector will project out over 30,000 invisible infrared dots. This system uses the infrared image and the infrared dots, and pushes them through neural networks to create a mathematical model of your face.

Neural networks

Your iPhone X (or newer) will check scans (or mathematical models) of your face against the one you've setup and stored on your device to see if it's a match, and if it is, it will unlock your phone or authorise a payment on Apple Pay.

This all happens in real-time and invisibly. Apple said it worked with thousands of people across the world and took over a billion images, and with that, it developed multiple neural networks to form its Face ID technology.

A11/A12 Bionic neural engine

In order to process all the data needed for Face ID, via machine learning, Apple had to develop the A11 Bionic neural engine. This chip was upgraded to the A12 Bionic neural engine in the iPhone XS, XS Max and XR devices, offering further improvements to the Face ID technology, followed by the A13 in the latest iPhones.

In a nutshell, the chips are specialised hardware built for a set of machine learning algorithms. They can handle hundreds of billions of operations per second and can therefore be used for technology, such as real-time Face ID recognition.

You, of course, don't really need to understand any of this, because as the user, Face ID is simple to use and works almost every time. It's 30 per cent faster now than it was when it first launched too and more angles are also supported, allowing you to unlock your device when it is flat on the table so long as you're close by whereas when Face ID first arrived, you had to pick your iPhone up.

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How do you set up Face ID?

Here's how to set up Face ID:

  1. Tap Settings
  2. Tap Face ID & Passcode
  3. Enter your passcode
  4. Tap 'Enroll Face' (under Face ID)
  5. Tap 'Get Started' and follow the on-screen prompts
  6. You will be asked to position your face within a frame
  7. Move your head around so it can be properly scanned

When setting up Face ID, you'll need to move your heard around slowly so that Face ID can fully recognise your face. The setup process will take two scans of your face and then that's it.

The scans enable Face ID to learn your face, so if you change your hair style, put on sunglasses, or grow a beard, Face ID should be able to adapt and still work. It will work both during the day and night, too.

Does Face ID work for payments?

Yes, aside from unlocking your iPhone X or newer device, Face ID can be used to pay for things via Apple Pay.

You'll need to double-tap the Power/Wake button on the side of your iPhone X or newer device as usual. You'll then need to look at your device to authenticate, and once authenticated, hold it near the contactless payment terminal.

Does Face ID work with apps?

Yes, Face ID also works with numerous third-party apps, including many banking apps and apps including Mint, One Password, and E-trade.

Is Face ID secure?

When Face ID launched, Apple said it worked hard to ensure Face ID can't be spoofed by things, like photographs. It even worked with professional mask-makers and make-up artists in Hollywood to train its neural networks and thus protect Face ID against those sort of bypass attempts.

Your face data is also protected by a secure enclave in the Bionic chips, and all the processing is done on the chips, whether that be the A11 or A12. That means your face data is not sent to a server.

Face ID also requires your attention to unlock, so if your eyes are closed, or if you're looking away, it's not going to unlock. According to Apple, the chances of someone being able to unlock your iPhone X (or newer) using Face ID is one in one million - an improvement over Touch ID, which Apple claimed has a false-positive rating of one in 50,000.

That statistic is lowered if you have a twin, so you will really need to set up a passcode in that instance.

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What if someone steals your iPhone?

According to Apple's software engineering chief, Craig Federighi - who notably replied to an email from a developer, Keith Krimbel, who asked the company what would stop a thief from taking someone's iPhone X (or newer), then pointing it at their face, and running off with the unlocked device - Apple made sure there were two mitigations in place: "If you don't stare at the phone, it won't unlock," he said.

"Also, if you grip the buttons on both sides of the phone when [you] hand it over, it will temporarily disable Face ID," Federighi explained. So, squeezing the buttons on both sides of iPhone X (or newer) disables Face ID.

What else do you need to know?

Face ID also works with emoji. Apple developed a type of emoji called Animoji when it launched the iPhone X in 2017 and it's since developed Memoji's too. These are animated emoji. You control these with your face, as they actually match the motions of your face.

To create and share Animoji or Memoji, use Apple's Messages app.