Apple has announced a new facial-recognition feature, which has been rumoured for months, but it's exclusive to the new iPhone X.

The technology, called Face ID, effectively replaces Touch ID fingerprint scanning. It uses a “TrueDepth camera system", which consists of sensors, cameras, and a dot projector, to create an incredibly detailed 3D map of your face, so every time you look at your phone, it'll conduct a secure authentication check to make not only unlocking but also paying "fast, easy, and intuitive", Apple promised.

Here's how Face ID works.

AppleApple unveils iPhone X with Super Retina Display and Face ID image 1

Apple has pulled the wraps off the iPhone X - or iPhone 10, as confirmed by Apple's Phil Schiller on stage - after months of rumours, leaks, and a few name changes along the way. One of the stand-out features is Apple's new A11 Bionic processor, which has a new Neural Engine that takes care of learning your face. It's capable of recognising you day or night, and it can adapt to changes such as facial hair.

The Face ID feature uses this processing hardware, along with the iPhone X's new TrueDepth camera system, to build a map of your face, which, when scanned, can be used for unlocking and processing payments. The iPhone X will be available in 64GB and 256GB options, and as expected, it won't be cheap. It starts at $999. You can order from 27 October, with shipping starting 3 November.

Go here to learn more about the device.

AppleWhat Is Apple Face Id And How Does It Work image 2

With iPhone X, your iPhone will remain locked until you look at it, and then, almost like magic, it'll recognise you. But it isn't magic; it's thanks to Face ID. Apple described it as the "future of how we will unlock our smartphones and protect our sensitive information". To make Face ID possible, Apple had to cram a lot of new hardware into a tiny area at the top of the display.

This area is dubbed the "TrueDepth camera system", and it is made up of a flood illuminator, infrared camera, front camera, and a dot projector. But that's not all. There's also a proximity sensor, ambient light sensor, and a speaker and microphone all packed in there.

AppleWhat Is Apple Face Id And How Does It Work image 9

Every time you glance at your iPhone X, the TrueDepth camera system will detect your face with the flood illuminator, even in the dark. The infrared camera will then take an image, and the dot projector will project out over 30,000 invisible infrared dots. The system uses the infrared image and the infrared dots, and then pushes them through neural networks to create a mathematical model of your face.

Your iPhone X will check that mathematical model against the one that you've set up and stored on your device to see if it's a match, and if it is, it will unlock your phone. 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 create this Face ID technology.

In order to process all the data needed for Face ID, via machine learning, Apple had to develop the new A11 Bionic neural engine. It's essentially the company's A11 Bionic chip with a built-in neural engine. In other words, it's specialised hardware built for a set of machine learning algorithms. Apple said its hardware and software teams had to collaborate in order to come up with this technology.

The neural engine is a processing system with a dual-core design that can handle 600 billion operations per second and can therefore be used for real-time Face ID recognition. You, of course, don't really need to understand any of this, because as the user, Apple has ensured that Face ID is just super fun and easy to use. When you set up Face ID, for instance, you just follow the on-screen prompts.

AppleWhat Is Apple Face Id And How Does It Work image 8

Here's how to set up Face ID (if you skip the enroll process when setting up your iPhone X):

  • Tap Settings
  • Tap Face ID & Passcode and enter your passcode
  • Tap Enroll Face (under Face ID)
  • Tap Get Started and follow the on-screen prompts
  • You will be asked to position your face within a frame
  • Move your head around so it can be properly scanned

When setting up Face ID, Apple said you just have to move your heard around slowly so that Face ID can fully recognise your face. That's it. You just do it once when you set it up - much like how you only have to set up Touch ID once on other iPhone models. Face ID will learn your face, so if you change your hair style or put on sunglasses or grow a beard, it will be able to adapt to you and just work.

It will work both during the day and night, too.

AppleWhat Is Apple Face Id And How Does It Work image 6

Yes, aside from unlocking your iPhone X, Face ID can be used to pay for things via Apple Pay. You just have double-tap the button on the side, then look at your iPhone X to authenticate, and hold it near the contactless payment terminal. Go here to learn more about Apple Pay.

Yes, Face ID also works with third-party apps, such as Mint, One Password, and E-trade at launch.

AppleWhat Is Apple Face Id And How Does It Work image 5

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 A11 Bionic chip, and all the processing is done on the chip.

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 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.

AppleWhat Is Apple Face Id And How Does It Work image 4

According to Apple's software engineering chief, Craig Federighi, who recently replied to an email from developer Keith Krimbel, who asked Federighi what would stop a thief from taking someone's iPhone X, then pointing it at their face, and running off with the unlocked device, Apple made sure there were two mitigiations 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 disables Face ID.

Face ID also works with emoji! Apple developed a new type of emoji called Animoji. These are animated emoji. You control these with your face, as they actually match the motions of your face. To create and share Animoji, use Apple's Messages app. At launch, there are over a dozen different Animoji you can make, including the poop emoji. Go here to learn more about animoji.