I. Introduction Android is a mobile operating system (OS) based on the Linux kernel and is currently developed by Google, with a user interface based on direct manipulation. Android is designed primarily for touchscreen mobile devices such as smartphones and tablets. It also provides specialized user interfaces for televisions, cars, and wrist watches. The OS uses touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching, and reverse pinching to manipulate on-sc