When an
HTTP client (generally a
Web browser) requests a
URL that points to a
directory structure instead of an actual Web page within the directory, the
Web server will generally serve a general page, which is often referred to as a main or "index" page.
If the server is unable to find a file with any of the names listed in its configuration, it may either return an error (generally 404 Not Found) or generate its own index page listing the files in the directory. It may also return a 403 Index Listing Forbidden. Usually this option is also configurable.
Since the index page is often the first page of a Web site that a user sees, it is sometimes used to offer a menu of language options for large Web sites that use geo targeting. It is also possible to not burden users with this step, particularly through content negotiation.
