Subdomain vs. Subdirectory

In site architecture, a subdomain is a completely separate, distinct partition of a primary domain, appearing before the root (e.g., `blog.website.com`). A subdirectory is a folder nested within the primary domain, appearing after the root (e.g., `website.com/blog/`). This distinction is arguably the most critical structural decision in SEO. Google’s algorithm treats subdomains as entirely separate entities, meaning the massive backlink authority (PageRank) earned by the primary domain does not automatically flow to the subdomain. Enterprise SEO strategy almost universally dictates using subdirectories, ensuring that every single article published consolidates maximum ranking power into the single, unified root domain.

Subdomain vs. Subdirectory Simplified

A subdomain is like building a completely separate house next door to your main website (blog.website.com). A subdirectory is like adding a new room inside your existing house (website.com/blog/). Because Google treats subdomains as separate websites, you should always use subdirectories so your main website gets all the credit.