Apple calls its fingerprint sensor “Touch ID.” Its function is actually quite limited as of now: you can use your fingerprint to unlock your phone instead of typing a passcode, or you can use it to buy apps in the App Store. In the future we hope that this function is opened to third-party developers because it holds a lot of promise.
Setup is super easy and takes less than a minute. Once the device recognizes and stores your Touch ID, the 5S is able to read your print very, very quickly. You’re also able to add multiple prints in case you want your spouse or other person to be able to access your phone.