Subdomains explained
What subdomains are, how they work, common uses, and how to create one on your domain.
You've probably seen web addresses like shop.yourbusiness.com or blog.yourbusiness.com. The part before the dot — shop or blog — is a subdomain. This guide explains what subdomains are and when they're useful.
Quick summary
A subdomain is a prefix added to your domain name that creates a separate, but related, address. For example, shop.yourbusiness.com is a subdomain of yourbusiness.com. Subdomains are free to create and can point to different servers or services than your main site.
What is a subdomain?
A subdomain is an extension of your domain name that sits to the left of the main domain. Your root domain is yourbusiness.com. A subdomain adds a prefix:
www.yourbusiness.com— the most common subdomain (thewwwprefix)shop.yourbusiness.com— might host an e-commerce storeblog.yourbusiness.com— might host a blog on a different platformapp.yourbusiness.com— might host a software applicationmail.yourbusiness.com— often used internally by email systems
You can create as many subdomains as you like. They're free — you don't pay extra to use them, and you don't need to register them separately.
How subdomains work
A subdomain is just a DNS record. To create one, you add an A record or CNAME record for the subdomain in your DNS settings.
For example, to create shop.yourbusiness.com, you'd add a DNS record:
| Name | Type | Value |
|---|---|---|
shop | A | IP address of the shop server |
Or, if the shop platform provides a URL rather than an IP address:
| Name | Type | Value |
|---|---|---|
shop | CNAME | shops.platform.com |
The subdomain can then point to a completely different server or platform than your main website.
Common uses for subdomains
| Subdomain | Common use |
|---|---|
www | The standard prefix for a website — nearly always set up |
shop | A separate e-commerce store |
blog | A blog hosted on a different platform |
app | A web application or client portal |
support | A help desk or support portal |
mail | Used internally by email infrastructure |
m | Mobile-specific version of a site (less common now) |
staging | A test/staging version of the site |
Subdomains vs subdirectories
You can structure your site in two ways:
| Approach | Example | Good for |
|---|---|---|
| Subdomain | blog.yourbusiness.com | Different platform, different team |
| Subdirectory | yourbusiness.com/blog | Same site, same platform |
For SEO purposes, subdirectories (folders on the same domain) generally share the domain's authority, while subdomains are treated more like separate sites by search engines. For most clients, a subdirectory is better for content like a blog. Subdomains make more sense when the content is genuinely separate (a different platform, a different product, etc.).
Common questions
Related guides
- www vs non-www
- DNS records explained (A, CNAME, MX, TXT)
- Pointing your domain to a new site
- What is DNS?
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