Domain redirection (also called URL redirection) allows you to redirect web requests for your domain name to content hosted on a different server (such as the free web space your ISP may provide).
URL redirection can be used as a cheap alternative to paid web hosting. You can host your site on a free server (with long path name) then redirect using a URL redirection server.
The actual URL is http://users.yourisp.com/~yourusername but you can use a short domain URL such as http://www.yourname.com.
Even if your long URL changes, the short domain name address you give out never changes. But you must update the destination URL on the URL redirection server to keep the URL accessible.