TL;DR
A subdomain is a domain under the DNS hierarchy, and it is mainly used to create multiple specific categories, landing pages or websites.
What is a subdomain?
A subdomain, named child domain as well, represents a domain that is under the Domain Name System (DNS) hierarchy of another domain.
Most subdomains are created to make the user experience more comfortable and the URLs easily memorable for specific pages of a website (such as Blog or Support)
When to use a subdomain
Subdomains have various reasons to be used:
- Create specific content categories, such as blog.yoursite.com, support.yoursite.com, store.yoursite.com.
- Share domain space with other people and customize their URL by offering a name.yoursite.com
- Create a separate category for login, or different services, such as an app (E.g., app.yoursite.com)
- Create multiple websites or landing pages
