There are two types of application state: persistent and transient. Persistent state exists when an application launches. It is saved to a private storage area called isolated storage and may include data such as configurable settings or files.
Transient state is discarded when an application is closed. It is stored at the application level in the
Microsoft.Phone.Shell.PhoneApplicationService.State dictionary or at the page level in the
There is a single
PhoneApplicationService instance for the entire app, and its state dictionary should be used only by objects running in the context of the application as a whole. A unique state dictionary is created for each page in your app, and you should ...