Touch ID is Apple's biometric fingerprint authentication technology. With it, the Home button can now unlock your iPhone 5s and authorize your purchases on the iTunes Store simply by reading and recognizing your fingerprints. In the perpetual battle between security and convenience, where many people would rather go without a passcode or strong password than fuss with anything complicated on mobile, Apple's Touch ID fingerprint identity sensor aims to do for authentication what [iCloud]/(iCloud) did for backup and restore - make it easy enough that people will actually use it.
How Touch ID works
A highly scratch-resistant sapphire glass lens protects the assembly and focuses the sensor, while a color-matched steel ring surrounds it, waiting to detect your finger. When that's triggered, the capacitive Touch ID sensor activates and takes what's effectively a high-resolution snapshot of your fingerprint. The fingerprint is compared against what's stored in the secure enclave on the Apple A7 chipset, and if the unique characteristics in the arches, loops, or whorls match, you're instantly authenticated and your iPhone 5s will unlock or your iTunes purchase will be authorized. So how does that all work?
Touch ID tries to balance convenience with security by letting you unlock your iPhone 5s with only a fingerprint. If the idea of frequently using a simple 4-digit passcode or strong alphanumeric password annoys you, Touch ID can let you enable one of those security methods while being able to easily, quickly get around it most of the time with just the touch of your finger. When you set up a new device, iOS will offer to walk you through Touch ID setup. Luckily, you decide against it at first, or turn it off at some point and then want to turn it back on, it's easy to do.
How to add fingerprints to Touch ID on your iPhone
Touch ID lets you have the security of a 4-digit passcode or the strength of an alphanumeric password, and yet still conveniently access your iPhone using your fingerprint. There are up to 5-slots in Touch ID, and you can use them to register your own fingers, a combination of yours and your family or colleagues, You can even temporarily register a travel-mate just in case of emergencies, without having to give them your passcode or password. Best of all, adding new fingerprints to Touch ID is easy.
Touch ID makes it easy to register your fingerprints so you can unlock your iPhone 5s or make iTunes purchases without a passcode or password. Once you've registered a few, however, the default labels Touch ID assigns them are pretty much useless when it comes to figuring out which is which. That's especially true if you've registered a family member's fingerprint so they can share your iPhone. Luckily Apple does let you rename Touch ID fingerprint labels to make them much easier to keep track of and trouble shoot later!
How to remove fingerprints from Touch ID on your iPhone
Touch ID lets you quickly and easily unlock your iPhone 5s and make iTunes purchases simply by placing your finger on the Home button. It's even a great way to temporarily give someone access to your iPhone without having to give them your passcode. Whether it's a co-worker on a trip, a family member who's visiting, or just someone you want to show off to, you can add and remove fingerprint whenever you like. Also, if a fingerprint becomes glitchy, you can remove it and redo it. That's because deleting Touch ID fingerprints is even easier than adding them!
How to turn off Touch ID for the Lock screen and revert to a passcode or password
Touch ID tries to balance convenience with security by letting you unlock your iPhone 5s with only a fingerprint. However, that won't be the right balance for everyone. Whether you simply don't like or trust biometrics, or it's just not right for your current situation and circumstances, Apple makes it easy to turn Touch ID off and a passcode or strong password on.
How to disable Touch ID for iTunes and App Store purchases
Touch ID is a super convenient way to unlock your iPhone 5s while keeping it secure at the same time. You can also use it to make App Store and iTunes purchases by default. However, if you've registered other family member's prints and you don't want them to be able to buy things on your account, or if you're just not comfortable with Touch ID purchases, you turn off iTunes purchases and not have to worry about it.