A web or URL redirect allows you to have one short name for a web page the has a long URL. For example you can have http://mysite.hopto.org redirect to http://www.asite.com/one/really/really/long/url/.
You can also use URL redirects to get around ISP’s that block port 80. For example http://mysite.hopto.org/ could redirect to a hostname running on a different port http://myothersite.hopto.org:8080/.