A web server can use different status codes in its response to the browser to indicate various kinds of success, failure or communicate other kinds of information. Next to HTTP 200 (Ok), the famous HTTP 404 (Not Found), another very useful status code is HTTP 307 (Temporary Redirect).

$ curl -i m.example.org
HTTP/1.1 307 Temporary Redirect
Location: www.example.org
Content-Type: text/html
Content-Length: 0

This can be useful if you want to indicate the redirection visibly to the user, as well as in cases where the server is depending on the “correct” or new domain for a service.

For making the same content/server accessible through different domains without necessarily re-writing the URL, use DNS CNAME and A/AAAA Records instead.