For this book, you will need a Mac computer that at least runs on OS X 10.7 Lion. Apple requires iOS applications to be compiled on a Mac, so our examples throughout the book will use Xamarin Studio on a Mac. You will also need a license of the business edition of Xamarin.Android and Xamarin.iOS. A free 30-day trial is also available. You can try the free Starter edition of Xamarin, but some of the more advanced examples will not work with that edition. Visit http://xamarin.com/download to download the appropriate software.