Difference Global.asax "a code for responding to application-level events raised by ASP.NET or by HttpModules..". Application can include only one Global.asax, but also it can use several HttpModules. Articles on HTTPModule http://www.15seconds.com/issue/020417.htm http://geekswithblogs.net/flanakin/articles/ModuleHandlerIntro.aspx http://www.builderau.com.au/program/dotnet/soa/Extend-ASP-NET-with-HTTP-modules/0,339028399,339284537,00.htm