Android is a Linux-based operating system, and it's a Google open source platform for mobile phones. Android is the world's most widely used smartphone operating system. Sources show that Apple's iOS stands second (https://www.idc.com/promo/smartphone-market-share/os). Android was developed by Google as an open and free option for hardware manufacturers and phone carriers. This makes Android the software of choice for companies who require a low-cost, customizable, lightweight operating system for their smart devices without developing a new operating system from scratch.

Android's open nature has further encouraged developers to build a large number of applications and upload them onto Google Play. Later, end users can download the applications from Android Market, which makes Android a powerful operating system. It is estimated that the Google Play Store has 3.3 million apps at the time of writing this book. More details on Android are covered in Chapter 7, Understanding Android.