Let’s say you are a webmaster into a few affiliate programs. You will have URLs which will look like;
or something like that.
The best way of getting visitors to not go directly to the site is making them believe (and the searchengines for that matter), that you are not an affiliate but that it is your site.
You do this by registering a domain and then using mod_rewrite in Apache:
Let’s say we registered www.someothersite.com and you want to rewrite, without users be able to see, this url to http://www.somesite.com/?id=xyz, you should set, in Apache;
RewriteRule (.*) http://www.somesite.com/$1?id=xyz [P]
No-one will be able to see the id in the URL without using frames, iframes etc.