We design apps for Android, iOS, and Windows by using C# or F# (Visual Basic is not supported at this time). To get started, install Visual Studio 2015, select the Custom option in the installer, and check the box under Cross Platform Mobile Development > C#/.NET (Xamarin). You can also start with the Xamarin Installer, which is required to install Xamarin for Visual Studio 2013.
If you already have Visual Studio 2015 installed, run the installer from Control Panel > Programs and Features and select the same Custom option for Xamarin as above.
Xamarin exposes the native functionality of Android, iOS, and Windows as .NET objects. Thus your apps have full access to native APIs and native user controls, and they’re just as responsive as apps written in the native platform languages.
After you create a project, you’ll leverage all of the productivity features of Visual Studio. For example, you’ll use a designer to create your pages, and use IntelliSense to explore the native API’s of the mobile platforms. When you’re ready to run your app and see how it looks, you can use the Visual Studio Emulator for Android or the Android SDK emulator, run Windows apps natively, or run Windows apps on the Windows Phone emulator. You can also use tethered Android and Windows devices directly. For iOS projects, connect to a networked Mac and start the Mac emulator from Visual Studio, or connect to a tethered device.Design one set of pages that render across all devices by using Xamarin.Forms
Depending on the complexity of your apps design, you might consider building it by using Xamarin.Forms templates in the Mobile Apps group of project templates. Xamarin.Forms is a UI toolkit that lets you create a single interface that you can share across Android, iOS, and Windows. When you compile a Xamarin.Forms solution, you’ll get an Android app, an iOS app, and a Windows app. For more details, see Learn about mobile development with Xamarin
Share code between Android, iOS, and Windows apps
If you’re not using Xamarin.Forms and choose to design for each platform individually, you can share most of your non-UI code between platform projects (Android, iOS, and Windows). This includes any business logic, cloud integration, database access, or any other code that targets the .NET Framework. The only code that you can’t share is code that targets a specific platform.