The iPhone 5S is a smartphone developed by Apple Inc. It is part of the iPhone line, and was released on September 20, 2013. Apple held an event to formally introduce the high-range phone, and its mid-range counterpart, the iPhone 5C, on September 10, 2013. As with the principle of the iPhone 3GS and iPhone 4S, the iPhone 5S is a revised version of its predecessor, iPhone 5. The phone maintains a very similar design to its predecessor, aside from the introduction of a new home button design using a laser-cut sapphire cover surrounded by a metallic ring, Touch ID, a fingerprint recognition system built directly into the home button which can be used to unlock the phone and authenticate Store and iTunes Store purchases, and an updated camera with a larger aperture and a dual-LED flash optimized for different color temperatures.