What is a subdomain
A subdomain is a prefix before the main domain (e.g., blog.example.com). Physically, a subdomain can be on the same server or a different one, but in DNS it is configured as a separate record.
Typical use cases
- blog. — for a blog or news section
- shop. — for an online store
- m. — for a mobile version (outdated with responsive design)
- support. — for a knowledge base and support
Subdomain vs subdirectory
Google officially says that subdomains and subdirectories (example.com/blog/) rank almost equally if content quality is the same. However, in practice, subdirectories often have an advantage because they inherit authority from the main domain, while a subdomain may start from zero.
- Link equity from the main domain may not automatically transfer to the subdomain.
- Subdomains require separate SEO optimization and link building.
- For a blog, the choice between subdomain and subdirectory is strategic.
If you want to promote unrelated business lines, a subdomain may be justified. For a regular blog on the main site, a subdirectory is usually preferable.
FAQ
Does a subdomain affect the main domain’s SEO?
Indirectly — links from the subdomain to the main domain are internal links. If the subdomain earns external backlinks, some weight may pass to the main domain.
How does Google crawl subdomains?
Typically as separate sites. A subdomain can have its own robots.txt, sitemap, and indexing settings independent of the main domain.
What is better for language versions: subdomain or subdirectory?
Google recommends subdirectories (example.com/en/), but subdomains (en.example.com) are also acceptable. Subdirectories are easier to manage and inherit authority.