What's the Difference Between a Subdomain and a Subdirectory?

Both let you organize a section of your site under its own address, but they work differently under the hood — and that difference occasionally matters more than it looks like it should.

Subdomain: its own separate space

A subdomain looks like blog.yoursite.com — technically a distinct address that sits in front of your main domain. It can even be hosted on entirely different infrastructure than the rest of your site.

Subdirectory: a folder within the same site

A subdirectory looks like yoursite.com/blog — a section living inside your existing site, sharing the same domain and infrastructure as everything else.

Why it matters beyond the URL format

Search engines have historically treated subdomains as somewhat separate entities from the main domain, which can mean the authority your main site has built doesn't always transfer as directly to a subdomain. A subdirectory keeps everything under one roof, so trust and ranking signals tend to reinforce the whole site together.

The practical takeaway

For most small businesses, keeping sections like a blog in a subdirectory rather than a subdomain is the safer default — one unified site building one unified reputation, rather than splitting it across two technically separate addresses.