For this book you will need a Mac computer running at least OS X 10.10. Apple requires iOS applications to be compiled on a Mac, so Xamarin has the same requirement. You can either use Xamarin Studio (best for Mac) or Visual Studio (best for Windows) as an IDE. Developers on Windows can work on iOS applications in Visual Studio by connecting to a Mac on their local network. Visit https://xamarin.com/download or https://visualstudio.com/download to download the appropriate software.