The Xamarin platform consists of many elements that allow you to develop applications for iOS and Android:

C# language – Allows you to use a familiar syntax and sophisticated features like Generics, LINQ, and the Parallel Task Library.

Mono .NET framework – Provides a cross-platform implementation of the extensive features in Microsoft’s .NET framework.**
Compiler – Depending on the platform, produces a native app (for example, iOS) or an integrated .NET application and runtime (for example, Android). The compiler also performs many optimizations for mobile deployment such as linking away unused code.
IDE tools – The Visual Studio on Mac and Windows allows you to create, build, and deploy Xamarin projects.