The configuration of your target platform dictates what kind of user interface (UI) and shell you need. Unlike Windows-based desktop platforms, Windows CE does not have a standard UI. Rather, the target hardware determines UI components. Although most platforms require some kind of UI, the interface may not resemble the one on a Windows-based desktop computer, and platforms incorporated into larger systems or computers may have no UI.
If you need a UI similar to that found on a Windows-based desktop computer, Windows CE provides a shell component for that purpose. However, if you need a different UI than the shell and the device manufacturer does not provide one, you must build your own using the Windows CE Shell API. For example, you can use this API to develop an application that allows the user to write directly on the device's screen with a stylus. Such capability is not included in the API for Windows-based desktop platforms.