What are Subdomains?
 

A subdomain, also known as a third-level domain, is an excellent method to create a distinct section of your website.
It combines a unique identifier with a domain name, effectively creating a domain within a domain.
The unique identifier simply substitutes the “www” in the web address. For instance, WorldPosta utilizes subdomains like mail.worldPosta.com and admin.worldposta.com to denote its mail and music services, all under the umbrella of www.worldposta.com.

Below is the model illustrating the structure of a subdomain.

http://

subdomain

.

domain

.

com

3rd level

2nd level

1st level