Xamarin Forms is a UI framework for building native cross-platform mobile apps with C#. You code your app only once, and let Xamarin compiler build your app for each platform.
You don't need to learn 4 different languages and presentation frameworks!
Apps built using Xamarin look and feel native, because they are :
- Native User Interfaces
- Native API Access
- Native Performance
C# Intermediate: Classes, Interfaces and Object-oriented Programming