Resource writers are used to write resources to files in a particular file format. Implement this interface if you want to control the way in which a resource file is written (for example, to store resources in something other than a .txt, .resx, or binary .resources file). Otherwise, use the default System.Resources.ResourceWriter class, which writes resources to a binary .resources file, or the System.Resources.ResXResourceWriter class, which writes resources to an XML resource (.resx) file.