An application configuration file contains settings specific to an application. This file contains configuration settings used by the common language runtime, such as assembly binding policy and remote object location, as well as settings used by the application.
The common language runtime checks the application configuration file for information that overrides the version information from the application. The application configuration file can be deployed with an application, but is not required for application execution. Usually, the retrieval by the runtime of this file is almost instantaneous, but in situations where the file is on a remote computer, such as in an Internet Explorer Web-based scenario, the configuration file must be downloaded.
The name and location of the application configuration file depend on the application's runtime host, which can be one of the following:
The configuration file for an application hosted by the executable host is located in the same directory as the application. The name of the configuration file is the name of the application with a .config extension. For example, an application called myApp.exe could have a configuration file called myApp.exe.config.
ASP.NET configuration files are named Web.config. Configuration files for ASP.NET applications inherit the settings of configuration files in the URL path. For more information about ASP.NET configuration files, see Configuring ASP.NET Applications.
If an application hosted in Internet Explorer has a configuration file, the location of this file is specified by an HTML <link> tag that points to a URL.
See the following topics in the .NET Framework SDK documentation: Configuring .NET Framework Applications, Common Language Runtime Configuration Settings.