One of the best features of iPhone 5S is Touch ID fingerprint sensor. As of now, the iPhone 5S is the only iPhone with an integrated fingerprint scanner built into the Home button. With Touch ID you can protect your data without having to type a passcode. Hold your finger on the home button for a second or two, and the access will be granted.
Touch ID is also capable of keeping tabs of multiple different fingerprints, so you won't have to worry about your friends buying embarrassing songs with your iTunes account with a single touch. The home button is now made of sapphire glass to reduce the potential for damaging one of the 5S' most notable features, and it's bounded by a steel “detection ring” that determines when your finger is on the home button and fires up the Touch ID sensor.
