Application data makes up the core of the data storage on Xamarin platforms and Windows Runtime. This data is specific to your application. It lives and eventually dies with it, and in most cases it is not relevant or even accessible by other applications running on the same device or even by the user who is using the application (at least directly).
The application has unrestricted access to application data, or so-called isolated storage, without having to ask for permission from the user or add a declaration and can (in most cases) write, read, and query items in this storage according to the type of the application data location.