Subdomains aren’t directly bad for SEO, but they’re not always the most strategic choice. Google states that subdomains and subdirectories are both fine, but subdomains are crawled and tracked separately. Your subdomain will likely be on its own for SEO factors like link equity, and it probably won’t pass link equity onto your main domain, either. Insights From Google logo “Google websearch is fine with using either subdomains or subdirectories…I recommend picking a setup that you can keep for longer.” JOHN MUELLER, GOOGLE Source Because link building can be one of the most challenging — and most vital — aspects of your SEO strategy, you’ll want a really good reason to choose a subdomain over a subdirectory. For example, if the subdomain’s topic is totally different from the main domain, a relevant backlink profile would also look completely different. In this case, a subdomain could work well. Keeping the new topic separate from the main site could help you build an SEO strategy specific to that niche, including its relevant keywords. Meanwhile, positioning it as a subdomain instead of an all-new domain allows you to maintain your brand equity.