Subdomains typically don't help SEO and can actually fragment your authority. Google treats subdomains as distinct entities from your root domain, so backlinks, content, and trust signals built on blog.yoursite.com don't directly strengthen yoursite.com the way blog.yoursite.com/blog would. This means you're building two separate SEO properties instead of one stronger asset. The subdirectory approach consolidates everything under one domain. All your content, backlinks, and crawl budget contribute to a single authority score. If you publish 200 articles under yoursite.com/blog, those ranking signals stack. Put them on blog.yoursite.com, and you're starting from zero domain authority each time. There are legitimate use cases for subdomains: geo-targeting different countries (ca.yoursite.com vs uk.yoursite.com), running a separate platform on different infrastructure (like a SaaS app versus marketing site), or isolating user-generated content you don't want affecting main site quality. But these are technical or strategic reasons, not SEO advantages. At Ottawa SEO, we run a 500+ domain portfolio and the pattern is clear. A single domain with organized subdirectories almost always outperforms the same content split across subdomains when total backlink profile and content volume are equal. The exception is when a subdomain becomes so authoritative on its own that it compensates for the split, but that requires massive dedicated link building. Google has softened its stance slightly over the years and can sometimes understand subdomain relationships, but you're still choosing the harder path. You need separate Search Console properties, separate sitemaps, and duplicated technical optimization. If you're debating this for a new blog or resource section, default to subdirectories unless you have a compelling non-SEO reason. If you inherited subdomains and they're already established with rankings and links, weigh the migration cost against the long-term consolidation benefit. Migrations done properly can take 3-6 months to stabilize in Canadian markets we track.