The httpd numerical codes returned when your
                web browser attempts to access a desired page.
                The numerical codes as errors are encountered
                directly.  The codes are generally recorded in
                your own system's access file when someone
                accesses any web page on the system.

          + 200 - OK, successful transmission. This is not an error.
          + 302 - Redirection to a new URL. The original page has moved.
            This is not an error; most browsers invisibly fetch the new
            page upon seeing this result.
          + 304 - Use local copy. This means that the copy of the file on
            the web server is not newer than the copy which your web
            browser or proxy server has cached locally, so there's no
            point in sending the file again. This is not an error.
          + 401 - Unauthorized. The user asked for a document but did not
            provide a valid username or password.
          + 403 - Forbidden. Access is explicitly denied to this
            document.
            (This might happen because the web server doesn't have read
            permission for the file you're requesting.)
          + 404 - Not found. This can also be sent if the server has been
            told to protect the document by telling unauthorized people
            that it doesn't exist.
          + 500 - Server error. Something went wrong with the web server
            and it couldn't give you a meaningful response. There is
            usually nothing that can be done from the browser end to fix
            this error; the server administrator will probably need to
            check the server's error log to see what happened.
          + 600 - Error due to network traffic. The connection was not
            completed due to load on the network.