A subdomain is a domain that is part of another (main) domain. It is an extension of the main domain name used to organize separate parts of a website. Subdomains are created to navigate to different sections of a website, and they allow websites to separate and organize content for a specific function. Subdomains are defined by editing the DNS zone file pertaining to the parent domain. They are often used by internet service providers supplying web services, who allocate one or more subdomains to their clients who do not have their domain name. This allows independent administration by the clients over their subdomain. Subdomains are also used by organizations that wish to assign a unique name to a particular department, function, or service related to the organization.
Some popular use cases of subdomains include:
- Creating a testing or staging version of a website
- Creating an online eCommerce store
- Creating a separate "help" section of a site
- Separating a blog from the rest of the website
- Organizing content from different locations of a franchise
- Denoting language or region
Subdomains are different from domains and subdirectories. A domain name is the unique name and address of the website, while a subdirectory is a folder within a domain that contains content.
