Android is a comprehensive open source platform designed for mobile devices. it is a truly open platform that is separating hardware from software that runs on it. This allows for a much larger number of devices to run same applications and creates a much richer ecosystem for developers and consumers to enjoy. Android is a purpose-built platform for mobile devices. Android was designed to run on all sorts of physical devices. Android applications are written in the Java programming language. The Android SDK tools compile the code - along with any data and resource files - into an Android package, an archive file with an .apk suffix.