Xamarin allows developers to write mobile apps once in C# and share the code across iOS, Android, and Windows platforms. It uses portable class libraries to share app logic and resources like images. Developers can build native user interfaces with Xamarin.Forms that deliver native experiences by mapping to each platform's native controls. Xamarin also enables access to device-specific features through standard UI controls rather than custom plugins. Developers can choose from a wide range of components to enhance functionality and performance.