Source : Free On-Line Dictionary of Computing

URL redirection
     
         (Or "URL forwarding")
     
        When a {web server} tells the {client} {browser} to obtain a
        certain requested page from a different location.  This is
        controlled by {directives} in the server's configuration files
        or a "Location: header output by a {CGI} script.
     
        The web server stores all its documents in a {directory tree}
        rooted at some configured directory, known as its "document
        root".  Normally the {URI} part of the {URL} (the part after
        the {hostname}) is used as a {relative path} from the document
        root to the desired file or directory.  A redirect directive
        allows the server administrator to specify exceptions to this
        general mapping from URL to file name by telling the browser
        "try this URL instead".  The new URL may be on the same server
        or a different one and may itself be subject to redirection.
     
        The user is normally unaware of this process except that it
        may introduce extra delay while the browser sends the new
        request and the browser will usually display the new URL
        rather than the one the user originally requested.
     
        (1997-07-15)