Solutions

On cPanel based systems, a subdomain is a method to map a hostname/url to a sub-directory. As an example:

• Assume your domain is yourdomain.com
• You install a forum into a directory in your web space called /forum/
• you can now access the forum as yourdomain.com/forum/
• You can turn the directory "forum" into a sub-domain from within your Control Panel. Now you can also access your forum as forum.yourdomain.com