What is a subdomain, and how does it differ from a subdirectory?

A subdomain adds a name before the main domain to distinguish a section of a website, such as blog.example.com; a subdirectory is a path after the domain, such as example.com/blog/. Both can organize content such as blogs and stores, but subdomains divide content at the domain-name level, while subdirectories organize it into paths under the same domain. Your choice should take into account how the content relates to the brand, whether it needs separate management, and the resources available for maintenance—not just which URL structure appears more favorable for search rankings.

Recognizing the structure in a URL: subdomains come before the main domain, subdirectories after it

Using example.com as the main domain, here is how the two structures work:

• blog.example.com: Adding blog before the main domain creates a subdomain for the blog.
• example.com/blog/: The main domain stays the same, while the /blog/ path organizes the blog content.

The two are not mutually exclusive. Subdirectories can have additional levels, such as example.com/blog/news/; subdomains can also have their own subdirectories, such as blog.example.com/news/. Using a subdomain therefore does not prevent a website from also organizing content into paths.

The differences extend beyond URLs to content strategy and management

Subdomains can use separate servers, IP addresses, and DNS settings, making them suitable for sections that need separate management. A subdomain may also be worth considering if the content requires a particular content management system or a different design. However, separate maintenance can increase technical and staffing demands; planning involves more than simply adding a name.

• Content that extends the same brand: For example, a clothing store adding styling articles for its existing audience could consider incorporating them into the original website through a subdirectory.
• Different businesses or purposes: For example, a group’s vegetable sales and food services businesses could consider using subdomains to separate them if they need distinct identities.

These are considerations, not fixed rules. A blog does not necessarily need a subdirectory, nor does a store necessarily need a subdomain. Too many subdomains or inconsistent designs may confuse users. Although subdirectories make it easier to maintain brand consistency, deeply nested structures can make paths hard to remember.

Do not equate structural differences directly with ranking performance

SEO recommendations are not entirely consistent. A 2025 article from Da Vinci Digital favors subdirectories as a way to consolidate authority on the main site. A Semrush article dated 2020, meanwhile, cites an earlier statement by John Mueller that Google web search can work with either structure and emphasizes that appropriate internal links help identify the relationship between sites.

The former is a service provider’s strategic judgment; the latter does not imply that every website would achieve identical rankings with either structure. When choosing a basic site structure, it is more useful to first clarify whether the content needs to be independent and whether the team can maintain it over time than to treat “subdirectories are always better” as a universal rule.