If you want to make an app for both iOS and Windows Phone, you need to write two different applications, which are not compatible with another. Both iOS 5 and W

If you want to make an app for both iOS and Windows Phone, you need to write two different applications, which are not compatible with another. Both iOS 5 and Windows Phone 7 have completely different APIs. If you add a new feature to one of the applications, it is not available on the other system. For every new operating system, you need to split your work. And your customers get an inconsistent and incompatible experience of your app across the different versions. This is fragmentation. From the ~100 different mobile operating systems that are in use today, maybe 95 can be targeted by a single code base, because they are all compatible with a common platform: Android 2.1 Eclair. You still have to consider the many different hardware configurations. But most of the work of porting your application from one system to another is gone. iOS and Windows Phone are complete end user operating systems, which are both made for a very specific hardware configuration and user experience. Android is a cross platform foundation that you can use to build those kinds of operating systems on. Is there a common application platform for both iOS and Windows Phone, and how often is it updated? The answer is: Yes, the web is such a platform. And it usually takes many years until an update is universally installed on all systems.