The Android OS is simple to learn, and Google provides many libraries to make it easy to implement rich and complex applications. The only aspect lacking, as mentioned by many in the Android developer community, is clear and well-explained documentation. The fact that Android is open source means anyone can dive in and reverse engineer some documentation. Many developer bulletin boards have excellent examples deduced using exactly this method. Still, a book that has a consistent treatment across all areas of the OS is useful. In addition, a clear working example is worth a thousand words of documentation. Developers faced with a problem usually prefer to do a form of extreme programming; that is, they find examples of working code that does something close to the solution and modify or extend it to meet their needs.The examples also serve as a way to see the coding style and help to shape other parts of the developer's code. This Android Cookbook serves to fill a need by providing many various self-contained recipes. As each recipe is introduced, the main concepts of the Android OS are also explained.