Android is a mobile operating system based on a modified version of the Linux kernel and other open-source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of developers known as the Open Handset Alliance, though its most widely used version is primarily developed by Google. It was unveiled in November 2007, with the first commercial Android device, the HTC Dream, being launched in September 2008.

Android has been the best-selling OS worldwide on smartphones since 2011 and on tablets since 2013. As of May 2021, it had over three billion monthly active users, the largest installed base of any operating system, and as of January 2021, the Google Play Store featured over 3 million apps. Android 13, released on August 15, 2022, is the latest version, and the recently released Android 12.1/12L includes improvements specific to foldable phones, tablets, desktop-sized screens and Chromebooks.

Android is a layered system, with the following layers:

• Linux kernel: The Linux kernel is the core of the Android operating system. It provides the basic services that all other layers rely on, such as memory management, process scheduling, and device drivers.
• Android Runtime (ART): ART is a virtual machine that executes Android apps. ART is used to optimize apps for the specific hardware they are running on, which can improve performance and battery life.
• Android framework: The Android framework provides a set of APIs that apps can use to access system services, such as the file system, the network, and the camera.
• Applications: Applications are the software that users interact with on their Android devices. Applications can be downloaded from the Google Play Store or from other sources.

The Android architecture is designed to be flexible and extensible. This allows Android to be adapted to a wide range of devices, from smartphones to tablets to TVs. Android is also designed to be secure. The operating system includes a number of security features, such as sandboxing and encryption, to protect users' data.

Android is a powerful and versatile operating system that is used by billions of people around the world. It is a popular choice for developers because it is open-source and easy to customize. Android is also a good choice for users because it is affordable and offers a wide range of features and apps.