Compilation Build Providers When you build an ASP.NET Web site, information contained in different types of files is compiled into assemblies that can be used on your Web pages. In ASP.NET 2.0 that compilation process takes place dynamically, so you don’t need to precompile. Dynamic compilation is now handled by extensible compilation build providers, which associate a particular file extension with a handler that knows how to compile that extension. Just drop files having specified extensions into the Code directory and they will be compiled in the background using the registered build providers. For example, .resx files can be dynamically compiled to resources that can be used for localization, .wsdl files are compiled to web service proxies, and .xsd files are compiled to typed DataSet objects. In addition to the built-in support for these file types, you can easily add support for your own additional extensions by implementing a custom build provider and registering it in Web.config.