Creating sub-domains gives you the ability to create shortcuts to special files, folders or websites. Say for example that you’re working with a freelance client and you want to point them to a folder on your site where they can see their new redesign. You could tell them. Go to http://iviewsource.com/clients/clientname/projects/website/redesign which is tough to remember and long to even try and say over the phone. With a subdomain shortcut, you can simply tell them to go to http://clientname.iviewsource.com and the server will automatically redirect them to the same folder.