Apple's latest and greatest iPhone 5S comes with an integrated fingerprint scanner to prevent unauthorised access and make it easier to get into the iTunes Store - is it another game-changer from the Cupertino company or a needless gimmick?
We take a look at the history of fingerprint scanners, the tech underpinning Apple's new toy and asks how much of a difference Touch ID will make to our mobile-powered lives.
How does it work?
The new Touch ID capacitive sensor sits under the familiar Home button, making it slightly less concave as a result. The button itself is made of laser-cut sapphire crystal (to avoid scratches) and surrounded by a stainless steel detection ring that can tell when you're trying to log in and when you're just trying to launch Siri (you don't actually need to press down to use the Touch ID technology).
The sensor is 170 microns thin (thinner than a human hair) and can scan your fingertips at a resolution of 500ppi in any direction.
It's also able to scan sub-epidermal skin layers — in other words, it'll still work in less-than-perfect conditions (with hands made raw from the cold British winter, for example).
Once your iPhone has a scan of your finger, it stores your fingerprint in a secure encrypted format on the integrated A7 processor. Apple is promising that the data is not passed to third-party apps (at least not yet) and doesn't leave your device - it isn't backed up to iCloud or stored on Apple's servers in any way. Whenever you match the fingerprint that's stored, you're in.
It's a bold move, if not a completely original one. Carolina Milanesi, Research VP at Gartner, thinks Apple's move can be a success: "Apple seems to have put a lot of work into the Touch ID - they absolutely know that it has to work flawlessly for users not to be put off.
"I think linking it to the iTunes login is a nice touch, no pun intended. Apple's timing is, in more cases than not, not a coincidence so I am sure we will see more biometrics in their devices." Keep your eyes on the new range of iPads.
Haven't we seen this before...?
Fingerprint-scanning technology has been in consumer devices for some time. IBM was rolling out fingerprint scanners in its laptops back in 2004, and we've seen it used in Microsoft's line of mice on and off since 2005.
2011's Motorola Atrix 4G had an integrated sensor in it until the unit was withdrawn due to poor sales. Apple hasn't come up with this technology all by itself, either: you might remember it acquired biometric security experts AuthenTec in June 2012 and the fingerprint authentication company Microlatch later in the same year.
AuthenTec's fingerprint scanning expertise has been seen in the past in handsets such as the waterproof Fujitsu F-01A.
Two weaknesses in the technology up to this point have prevented it from gaining serious traction: firstly, it hasn't always worked with any great degree of accuracy, leading to users jabbing at their handsets in frustration.
Secondly, it has been known to be easily fooled in the past (using plasticine or photocopies for example). If Apple can overcome these problems — and early hands-on impressions from the launch event are that it has a good chance — then we might eventually see sensors such as the one in the iPhone 5S replace passwords and passcodes for good.
Tony Cripps, principal device analyst at Ovum, spoke to us about Apple's implementation of the technology: "The word from the event is that the Touch ID system actually works very well. The risk with many fingerprint ID systems historically has been their failure to recognise repeatedly and consistently the fingerprint registered on them.
"First impressions imply Apple has overcome this problem, which could lead to wider acceptance in other CE devices and by other device makers."
Fingerprint sensing security isn't perfect, and we don't know yet whether a lifted fingerprint (from the back of the case, perhaps) would be enough to unlock the iPhone 5S.
Your average pickpocket doesn't carry a forensics kit along with him, but we'll have to wait and see how robust Touch ID is — brace yourselves for plenty of in-depth hacking attempts in the tech press over the coming weeks ("How To Unlock An iPhone 5s With A Biro And Sellotape").
At this stage, we just don't know how strong Apple's tech is — our initial impressions are that Touch ID works "incredibly well", but it's still early days.
Will it make a difference?
Apple is touting Touch ID primarily as a more secure version of the passcode and according to Senior Vice President Phil Schiller only half of us ever bother setting up a passcode anyway. The next time someone steals your phone in the street, they'll either have to take your finger along with them or force you to unlock it first.
It saves you from forgetting your passcode and reduces the security risk caused by users who set up the same code on all of their devices and services for convenience's sake. Even if hacks to circumvent Touch ID eventually come to light, it's still a significant upgrade in terms of the security of your iPhone.
However, it's also about ease-of-use and unlocking your mobile with one press rather than four or five. With its tight iTunes integration you'll be able to get new apps, movies and music without having to enter your Apple password each time.
Further down the line we might see Apple embedding the technology in iCloud, on your Mac or even in high street retail stores to let you prove you are who you say you are. From there, it's obvious how the principle could extent to banking or mobile payments (think Passbook, for example).
Ian Hogg, Director of Mobile Analysis at IHS Electronics & Media, explained that iOS7 has a big part to play too: "Mobile security that protects a handset is important to secure the information that users have on their device - banking passwords, purchase histories, email addresses, contacts.
"Apple is adding significant new features that make it harder for a thief to circumvent 'find my phone' and 'remote wipe' features."
For the time being though a revolution in biometrics is still some way off. For now, Touch ID makes it easier to use your iPhone and keeps it more secure at the same time. Only if and when the technology expands beyond your personal handset will its safety be seriously called into question.
"The concern some users may have, as with the current furore over online services," adds Tony Cripps, "is more that Apple itself might volunteer user information seemingly protected behind that fingerprint to government agencies. How consumers ultimately choose to respond to such concerns in the long run is yet to be seen."
It seems everyone agrees that we need a safer replacement for passwords. Tattoos and pills have been touted as possible personal identification solutions of the future, but the launch of the iPhone 5s has put fingerprint sensing technology back in the spotlight.
Only when the phone is out and being put through its paces will we know just how well it works and how far users are ready to trust it.
Here's everything you need to know about the iPhone 5S: