Although Google claims that you can go with either as both will be indexed, it does make difference in terms of SEO.
Let’s summarise this to address the question: Do subdomains have an impact on SEO?
Table of Contents
Google’s interpretation of a subdomain
Google sees and indexes your domain and subdomain as two separate websites. Even though both sites will be indexed they will be indexed separately. Not as a single entity. This will bifurcate our SEO efforts.
Keeping blog content separately on a subdomain will decrease the SEO value, will have separate page authority, we might lose some visitors to take action on our main site and also we’ll have distinct ranking factors for both sites.
Do subdomains add to our total pages or SEO
When blog posts continue to be published on a separate domain (subdomain), that content will no longer be considered a ranking factor for our main site.
Quality content is crucial when it comes to SEO and ranking. Because Google prefers to rank content-rich websites in order to foster confidence among its users.
Another important point to understand is subdomains inherit the authority from the main site. As a result, increasing the domain authority of the primary site is critical.
Content Syndication of subdomains
The social shares and the content republishing on other platforms like a medium will benefit our subdomain, they won’t help our main site’s authority if we use the subdomain.
However, if we have a blog on our main site, the backlinks and social media shares generated by the content will assist the main site’s other pages to rank higher and increase the link profile of the overall website.
Internal linking isn’t helped by subdomains
Any links from the subdomain to the root will not be considered internal linking and may cause more harm than good because they will be perceived as external links from a lower authority domain.
Competing against ourself
When our main domain and subdomain are both optimized for the same search term (keyword), they end up competing.
When to use subdomains
When we have content that is totally different from the main site’s purpose like the app, support, and training then we can use subdomains.
When your purpose is just to blog about your business or any niche I don’t find any substantial reason to go with the sub-domain.
To wrap up
Subdomains don’t contribute to the authority of your main site. It is like competing with ourselves for our focus keywords. Internal links and external links for a subdomain aren’t that helpful for the main site. It is tricker to track the performance as a distinct site in analytics tools.
In short when you are providing any other service like the dashboard for your clients then it is a good idea to do it on a separate domain otherwise for blogs you can keep it on the same domain.