What is a Subdomain

In this tutorial you will learn about subdomains. First, what is a subdomain? Essentially, a subdomain is a domain which is the “child” of a “parent” domain. Whereas a domain can be standalone, a subdomain is always associated with a parent.
Step # 1 – Viewing an Example of a Subdomain
One of the most famous examples of a subdomain are the About sites. For instance, go to “about.com.” About.com is a website about everything. It is a parent domain. Now, go
to “southernfood.about.com.” This is a subdomain of “about.com” which specifically deals with American southern cuisine.
The main About.com domain

Step # 2 – Understanding the Importance of Subdomains
Subdomains are important because they allow content to be organized. About.com is the perfect example, because although it is a website about everything, it organizes its content into subdomains, which makes it easier for users to access information which is relevant to them. Viewing subdomains in this manner makes it easier to understand what is a subdomain.
The Southern Food subdomain of About.com