At the recent iPhone event Apple unveiled a new feature that will allows users to unlock their iPhone X simply by looking at it. Witchcraft! we hear you cry. But no, this is Face ID, a camera-based facial recognition system that Apple is positioning as the future of smartphone security.

In this article we take a look at how Face ID works, why the face looks set to replace the fingerprint as a means of biometric security, and how Face ID and Touch ID compare for reliability, security and privacy.

What is Face ID?

Since the launch of the iPhone 5s, Touch ID has been the fast and efficient way to unlock an iOS device thanks to the fingerprint sensor hidden in the Home button.

While this has proven to be a reliable method of security, it does pose one problem: what happens if you need to get rid of the big button on the front of the phone to make room for more screen space?

Many Android devices have already addressed this by placing fingerprint sensors on the back or side of their devices, meaning the front is a smooth panel of uninterrupted glass. Apple, of course, decided to Think Different.

With the introduction of the iPhone X (pronounced 'ten') comes Face ID, which uses the new TrueDepth camera to create a 3D map of your face. This means that, just as your fingerprint was scanned on Touch ID to open your phone, now your looks will get you everywhere.

How does Face ID work?

The TrueDepth camera on the iPhone X is made up of several different elements, all of which combine to make your 3D facial image.

First there's the Dot Projector that, as the name suggests, projects a number of invisible dots on to your face: 30,000 of them, in fact! These mark out the various contours of your visage, creating a detailed map.

Face ID v Touch ID

Reading this map is the infrared camera, which records the placement of every dot, then sends the data directly to the Secure Enclave within the iPhone X's A11 Bionic processor chip.

Here it is checked against the pre-scanned image to ensure that the correct face is being seen, all without any info being sent out to external servers. If a match is found, the phone is unlocked, all within a blink of an eye.

Don't blink too slowly, though, as Face ID only works if your eyes are open and you're looking directly at the camera. This is a sensible security feature to prevent anybody lifting your phone while you sleep and using your slumbering countenance to access the device. (Some have wondered how well this will suit those with disabilities that prevent them from opening their eyes, but it appears you can turn the option off in accessibility settings.)

Thanks to the Flood Illuminator also found in the TrueDepth camera, Face ID can even see you in the dark, so the sleep scenario isn't as far-fetched as it might sound.

Hopefully there is some way for the device to also register when you're in the cinema, so it can resolutely refuse to let you use your phone during a screening. If not then we can only hope that the British version of the iPhone X is resistant to loud, annoyed tutting.

How reliable will Face ID be, compared to Touch ID?

As Face ID is yet to make its way into the wild, we can't be certain how accurate and robust the recognition protocols will be.

On its first public outing the feature actually failed to open for Apple executive Craig Federighi, which caused a moment of embarrassment in front of millions of viewers.

Face ID v Touch ID

On deeper inspection, it looks like the iPhone had been turned off, or idle for some time, which triggered the need for a passcode to be entered before it would open. This is a security feature also found on Touch ID-enabled devices, but one that was unwelcome at the prestige event.

Federighi recovered with his usual panache, and for the rest of the live demo Face ID worked impeccably, opening the device on several occasions.

Just as Touch ID can have a habit of not recognising fingerprints from time to time (for advice on dealing with these, see What to do if Touch ID is not working), Face ID will no doubt have its dodgy moments. This is nothing to worry about, though, as users are required to create a passcode while setting up the feature, so you'll never truly be locked out of your iPhone.

Is Face ID more secure than Touch ID?

For years we've all been told about the uniqueness of our fingerprints. In many ways, this contributed to the public's quick adoption of Touch ID as a security feature, and even as a way to pay for things by using Apple Pay.

Somehow, it feels like a camera looking at our face is less secure and reliable. What if the lens is a bit dirty, or I'm wearing different glasses? Well, it seems Apple has been thorough in its implementation of Face ID, and announced some rather surprising figures at the launch event.

With Touch ID, it stated that there was a 1 in 50,000 chance that someone would be able to open your phone with their fingerprint. These numbers were a little better for Face ID, at 1 in 1,000,000.

Face ID v Touch ID

That's a pretty staggering increase, by anyone's standards.

Apple also announced that Face ID would be able to recognise you if you wore a hat, glasses, or even if you grew a beard. We couldn't confirm whether the TrueDepth camera could actually look into your soul, but it does seem a distinct possibility.

Those wanting to find out more about the security aspect should take a look at our article on how secure Face ID is

Can I use Face ID on my iPhone?

At the moment, due to its reliance on the TrueDepth camera and A11 Bionic processor, Face ID will only be available on the iPhone X. If you simply must have it, then you'll be able to pre-order the iPhone X from Apple from 27 October. (It goes on sale on 3 November.)

Those with the new iPhone 8, 8 Plus, or any of the preceding models will have to settle for Touch ID. But, to be fair, Touch ID remains an excellent way to quickly open and use your iOS device.

With Face ID Apple has shown its vision for the future, and it appears that the future will be looking right back at us.