Xamarin.Forms is a cross-platform UI framework. It is designed for .NET developers to be able define the UI in a platform independent manner using primarily C# and XAML.  Xamarin at it’s core provides a 1-to-1 API mapping to the native platform, so the UI is compiled down to the appropriate native UI engine, providing a native experience for the end user on Android, iOS, and Universal Windows Application alike.

The idea here is to write code in C# using .NET toolset and development environment while also sharing as much code as possible. The end product will have a native experience on all the supported target platforms. Since the common project is a .NET Standard project, developers have access to a vast amount of compatible libraries, which is a major benefit!

Xamarin Forms was introduced in May, 2014. Xamarin was primarily supported by Microsoft and now it is open source [ https://github.com/xamarin/Xamarin.Forms ]. At the time of writing this, Xamarin.Forms is almost at it’s fourth major iteration, Xamarin.Forms 4.0.

Following are some great educational material for Xamarin:

Microsoft Docs: https://docs.microsoft.com/en-us/xamarin/xamarin-forms/

Xamarin University (moving to Microsoft Learn): https://university.xamarin.com/

Xamarin Blogs: https://blog.xamarin.com/