As you can recall from, Chapter 1, The Anatomy of an Android App, Android apps run within the Dalvik VM, and we now know that Mono apps run within the Mono CLR. So how does a Xamarin.Android app run? A simple answer is that it uses both the Mono CLR and the Dalvik VM. The following diagram depicts how the runtimes coexist:

Xamarin.Android applications use both Mono CLR and the Dalvik VM side by side and run on top of the Linux kernel. The .Net API resides as a part of the Mono CLR and provides a set of classes (for example, System.Data, System.Net, System.IO, and so on.) to access various device OS features. However, with .Net APIs, you cannot directly access most of the device-specific features, such as Audio, Telephony, OpenGL, and so on. They are made available as a part of the Android SDK or as Java API and can be accessed using the Android binding libraries. The following section covers more on the Android binding libraries.

Since Android 5.0 (Lollipop) release...