What is .XAP file in Silverlight? XAP is combination of 2 or more files which have .dll,.XAML and some resource files. In real .XAP is a COMPRESSED file for silverlight application. Now comes to the files it contains below is the list for the same:- (1)AppManifest.xaml (2)COMPILEASSEMBLY of silverlight project(.dll) file (3)Other RESOURCES of silverlight application. Usualy Visual studio CREATES 2 files while creating project (i)App.XAML (ii)Page.xaml