App development is different from traditional software development. You must design to take advantage of, and be aware of, the impact of the mobile operating system and the hardware that the app is running on. If you do not design your app to account for these differences in the device, you will ensure that your app does not get much use. Android and iOS devices have many similarities and differences that require planning when you are developing an app that will run on both device families. To learn both platforms and learn the differences between them, you will develop the same app for both platforms in the next two sections of the book.