Touch ID, the feature can be used to unlock the device, as well as make purchases in the iTunes, iBooks and App stores.
As with virtually every other new feature in the iPhone 5s, this addition was predicted -- which is to say, most likely leaked -- well in advance of the smartphone's well-hyped unveiling. Then again, Apple signaled its biometric intentions in July 2012 with its $356 million acquisition of fingerprint reader manufacturer Authentec.
One year later, cue the debut of Touch ID, a 500 ppi scanner that "uses advanced capacitive touch to take, in essence, a high-resolution image of your fingerprint from the sub-epidermal layers of your skin," according to Apple. "It then intelligently analyzes this information with a remarkable degree of detail and precision."
[ Updating is not an option. See Apple iOS 7: 6 Reasons Enterprises Must Upgrade . ]
What are the potential security upsides of having an Apple-designed fingerprint scanner? Here are nine related facts:
1. Sensor Lives Where You Most Tap
The iPhone 5s puts the fingertip sensor inside the home button, meaning it's easy to find and use. "If you're lucky enough to get your fingers on an iPhone 5s, you will notice that the new Home button -- ironically, the moving part of an iPhone that most often breaks in my experience -- has a stainless steel ring around it, denoting where the Touch ID sensor is located," said security researcher Graham Cluley in a blog post. Still, Apple said the home button is now made from sapphire glass to make it more durable.
Users can store more than one fingerprint to make it easier to unlock an iPhone no matter how they're holding it. On the family and friends front, the iPhone 5s will store fingerprints -- appropriately enough -- for up to five people.
2. First Impression: Fingerprint Scanning Works
John Gruber, who runs the technology blog Daring Fireball -- and who's seen by many as an Apple evangelist -- got his hands on an iPhone 5s Tuesday and reported that Touch ID was "fairly quick to train, and once trained, it is really fast, and in my brief hands-on testing, very accurate." From a usability standpoint, waking the device involves pressing the home button, and leaving it there a moment longer leads to authentication and an unlock. "It's very impressive technology. I already feel silly tapping in my passcode to unlock my iPhone," he said.
3. Only Apple Touches Fingers
Touch ID isn't meant to replace all passwords or passcodes. In fact, use of the fingertip sensor has been restricted to unlocking the device or making purchases from Apple. So far, other iOS developers don't get to access to Touch ID. "It cannot currently be used to unlock anything else on your iPhone. In other words, it can't access iCloud, or your Keychain, or be used to log into third-party apps like Facebook," said Cluley.
4. Feature To Beat: Fingertip Sensor?
Given Apple's trend-setting capabilities, expect other smartphone manufacturers to follow suit on the biometric front. "Fingerprint-based identification technology is likely to be introduced by other manufacturers in the near future and may catch on as a mode of payment elsewhere as a result," said Ronan de Renesse, a principal analyst at market researcher Analysys Mason, in an emailed research note. He noted that Touch ID -- together with iOS 7, the 64-bit A7 processor and an improved camera -- represent Apple's bid to be more competitive in "in the upper-end of the smartphone market."