Subdomains are a way of creating separate Web Hosting accounts within your master Web Hosting account, which are accessed as separate URLs. For example,
you could set up a "timber" subdomain on your master Web Hosting account "hardware.com", which would be accessed as "timber.hardware.com".
A lot of larger businesses use subdomains to establish branding and focus on separate product lines, because a subdomain creates
a separate URL and web presence. However, you do not create a new the Web Hosting CPanel 4 when you create a subdomain. You still perform most administration functions for the subdomain through
your master the Web Hosting CPanel 4.
Practically, a subdomain is a sub folder within the public_http level of your Web Hosting account that has it's own cgi-bin directory. The "timber" example above creates a new top-level folder called timber, with a cgi-bin sub-folder. Upload your files for the subdomain to this location, including a separate home file (such as index.htm).
Currently you can not create email Web Hosting accounts with the subdomain extension. A workaround for this is to create an Web Hosting account called "sales-timber@hardware.com", or similar.
To add a subdomain:
Click on the Sub Domains link in the Web Hosting CPanel 4 Settings area.
Note: You can only successfully create a new subdomain once your DNS number has successfully propagated for this Web Hosting account.
Enter the text for the new subdomain in the field in the available field. You must conform to domain name conventions for the addition to the name.
Click on the
button. Click on the Sub Domains link to return to the Subdomains window to confirm that it has been added. A folder with the same name as the subdomain has
now been added to your public_html folder, with a cgi-bin sub-folder (if CGI scripts are enabled on your Web Hosting account).

Topics:
Subdomain Statistics
Adding subdomain redirection
Deleting a subdomain