As the name suggests, it does not have a new domain name. It is a is a second website, with its own unique content, but will always carry the name of the parent/main domain.
As an example, you have the domain domain1.com. Its document root will be /home/username/public_html (this could vary at times). Contents will be loaded from this location when domain1 is accessed in the browser.
You decide to have a wordpress installation in a sub directory blog (/home/username/public_html/blog), which you intend to access as blog.domain1.com
This is when you go for a subdomain. The same contents can be accessed as domain1.com/blog or blog.domain1.com
If you own domain1.com, you can have many subdomains (depending on the plan you are on) as blog.domain1.com, help.domain1.com, gallery.domain1.com
Below is step by step, how to create a subdomain in cpanel :
- Login to Cpanel
- Click on subdomains
- Enter subdomain name you wish to use
- Choose document root name or leave blank
- Click on create