here are two xaml files are created when a new project in Silverlight is created through Visual Studio.
1. App.xaml – This file is used for declaring shared resources like style objects, brushes etc and for handling global application level event. The following are the default events created in App.xaml.cs file.
Application_Startup
Application_Exit
Application_UnhandledException
ReportErrorToDOM
2. MainPage.xaml or Page.xaml – This file is the default page of the Silverlight application at the time of silverlight application’s execution. This is similar to default.aspx page of ast.net application.