Xamarin.Forms allows developers to build native mobile apps for iOS, Android, and Windows from shared C# code. Xamarin.Forms 3.0 focuses on stability, performance, and features to make apps on different devices easier to create. New features in 3.0 include FlexLayout for distribution and adaptability, a Visual State Manager, StyleSheets for CSS-like styling, and right-to-left localization support. The document also provides a link to demo code and contact information for the author.