Android API Level 21
Android API Level 21, also known as Android 5.0 Lollipop, is a specific version of the Android operating system released by Google in 2014. It introduced major changes including the Material Design language, improved performance with the Android Runtime (ART), and new APIs for features like notifications, camera, and battery usage. Developers target this API level to ensure compatibility with devices running Android 5.0 and later, while accessing its enhanced capabilities.
Developers should learn and use Android API Level 21 when building apps that require modern Android features such as Material Design components, improved notification systems, or support for devices from 2014 onward. It is essential for apps targeting a broad user base on Android 5.0+ and for leveraging performance optimizations like ART, but note that newer API levels offer additional features and security updates.