You’ve probably noticed that URLs sometimes have an extra word before the main domain name. Instead of just example.com, you might see blog.example.com or shop.example.com. That extra word is called a subdomain.

Diagram showing how a subdomain fits into a URL structure

Click from a homepage into the blog and the address might change from example.com to blog.example.com. You have not left the site. You have moved into a section the owner chose to run separately.

Understanding Subdomains

A subdomain is a prefix added to the front of a domain name that lets you run part of your site as its own section, like a blog, a store, or a help center.

Read a domain right to left and it comes apart in three pieces. In blog.example.com, com is the top-level domain, example is the second-level domain you registered, and blog is the subdomain sitting in front of both.

You can create subdomains yourself at any time, and you do not pay extra for them. That is the practical difference between a subdomain and a whole new domain: one is a free section of something you already own, the other is a separate purchase.

Is www a Subdomain?

Technically, yes. www is a subdomain like any other. It is a leftover convention from the early web, when it signalled which machine served the web pages as opposed to mail or files.

It carries no special weight now. example.com and www.example.com can serve identical pages, and most sites pick one and redirect the other so Google does not see two versions of everything.

Why Use Subdomains?

A subdomain makes sense when a section of your site is different enough that it wants its own setup: a separate platform, a separate team, or a separate audience.

  • A store on different software. Your main site runs WordPress and your shop runs Shopify, so the shop lives at shop.example.com.
  • A help center or docs. Support content usually runs on its own tool, which is why so many are at help.example.com or docs.example.com.
  • Language or region. Wikipedia does this at scale, with en.wikipedia.org for English and es.wikipedia.org for Spanish.
  • Environments you do not want indexed. Staging and test sites usually sit on a subdomain like staging.example.com, blocked from search.

The common thread: each one is genuinely its own thing. If a section is just more pages of the same site, a subdomain is usually more setup than it is worth.

How to Create a Subdomain

The exact screens depend on your host, but the shape is the same everywhere.

  1. Pick the name. Short and obvious beats clever. blog, shop, help, docs.
  2. Open your DNS settings. That might be cPanel, your host’s own dashboard, or your registrar if your DNS lives there. If you use Cloudflare, it is in the DNS tab.
  3. Add the record. Point the subdomain where it needs to go: an A record for an IP address, or a CNAME for another hostname, which is what most hosted platforms hand you.
  4. Wait for it to resolve. Usually a few minutes. It can take up to 24 hours if the old record was cached with a long TTL.
  5. Add it to Search Console separately. This is the step people miss. Google treats each subdomain as its own property, so blog.example.com needs its own verification and its own sitemap.

Subdomain or Subfolder for a Blog?

This is the decision most people actually arrive here for, and the honest answer has two halves.

Google’s position is that it sees both the same. John Mueller has said so repeatedly, adding that he would keep things on one site where you can and save subdomains for content that is genuinely different. So the idea that Google automatically discounts a subdomain is not something Google says.

In practice, plenty of SEOs still report better results after moving a blog from blog.example.com to example.com/blog/. Those are observations rather than a documented rule, and a move like that usually comes bundled with other changes, so it is hard to credit the URL alone.

What that leaves you with is a practical test. If the content exists to support the main site and you want it feeding the same brand, put it in a subfolder. If it runs on different software, serves a different audience, or would happily stand alone, a subdomain is the cleaner choice. Do not move an established blog just because a checklist told you to.

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