The HTTP error message returned to the browser by the Web server when a requested Web page is not available. The error occurs because the page no longer exists or is restricted. The 404 error can be modified by the site's Webmaster to a more user-friendly message.
Like a telephone book, a link to a Web page (URL) is static. Although software can be used to search each link on a site to ensure the target pages still exist, it cannot automatically find new addresses if the pages are no longer present. See 404
, HTTP return codes
, 500 error
, link rot
and moved to Atlanta