It is a decision made in five minutes that then shapes years of work. You are about to add a blog, a store, or a help section to your site, and you have to choose between a subdomain and a subfolder. Changing your mind later means mass redirects and a period of instability in search results, so it pays to understand what you are choosing.
The technical difference, in one line
A subfolder is a path inside the same site: yoursite.com/blog/. It lives in the same account, in the same public folder, under the same certificate.
A subdomain is, for practical purposes, another site: blog.yoursite.com. It has its own DNS record, its own folder, and often its own installation and its own certificate.
That technical difference explains everything else.
How search engines see it
This is the point that generates the most argument, and it needs nuance, because absolute claims on this topic are usually wrong.
Google treats subdomains as entities that may be independent. It understands that blog.yoursite.com and yoursite.com are related, but it does not assume they are the same thing. In practice, the authority your blog earns does not transfer to the main domain with the same strength as it would from a subfolder.
With a subfolder, by contrast, everything you publish adds to the same site. Every article that earns links strengthens the whole domain, including the commercial pages. If your goal is for the blog to push the pages that sell, the subfolder is clearly better.
The important exception: when the content is genuinely of a different nature. If you have a product plus a huge community with user-generated content, keeping that on a subdomain prevents quality problems on one side from tainting perception of the other. That is an isolation decision, not pure SEO.
When the subfolder wins
For the vast majority of sites, the right answer is the subfolder. The clear cases:
A blog supporting the business. The goal is attracting visits with useful content and moving them to service or product pages. Everything the blog earns should accrue to the same domain.
A store inside a content site. Same logic: the content builds trust and authority that the store then benefits from.
A help or documentation section. This is content answering purchase questions and reinforcing the brand. The more integrated, the better.
Other-language versions of a small site. With language tags set correctly, subfolders work very well and are easier to administer.
When a subdomain makes sense
There are situations where the subdomain is the right call, and almost all of them concern technical separation rather than marketing.
A staging environment. A copy of the site for testing changes before applying them in production must be separate, and also blocked from search engines. Here the subdomain is the natural fit.
An application on different technology. If your main site is WordPress and you need a client portal built on something else, dropping it in a subfolder creates configuration and rewrite conflicts. Separating it is cleaner.
A service with very different resource needs. A course platform with video, or a tool that eats memory, is better isolated so a spike there does not take down the commercial site.
Third-party content. If you let people publish pages inside your service, isolating it protects your main domain if someone posts something problematic.
What nobody mentions: the daily work
Beyond SEO, there are practical differences you feel every week.
With a subdomain you have two installations to update, two sets of plugins, two themes, two backups to verify. If both are WordPress, it is literally double the maintenance.
With a subfolder, if it is the same system, there is nothing extra: the blog is just another section of the site you already manage.
It also changes the browsing experience. Moving from yoursite.com to blog.yoursite.com technically means changing sites: sessions are not shared automatically, and if you have a client area, someone logged into the main site is not necessarily logged into the subdomain without extra configuration.
How each one is implemented
Creating a subdomain in cPanel is a matter of one form: you pick the name, the panel creates the DNS record and the folder. Then you install whatever you want inside. A detail people forget often: verify that the SSL certificate covers the subdomain. Wildcard certificates cover all subdomains at one level; plain certificates do not.
The subfolder depends on what you are putting there. If it is a section of the same platform, you create it from inside the system. If it is a separate installation inside a folder, be careful with the main site rewrite rules, which can capture the subfolder paths and break it. The fix is adding an explicit exception before the catch-all rule.
Analytics and cookies: a detail that bites later
One consequence people discover too late concerns measurement. If your blog sits on a subdomain and the store on the main domain, by default your analytics tool treats a visitor moving from one to the other as two separate sessions from two different sources. The blog ends up looking like it converts nothing, and the store looks like it receives mysterious direct traffic. It is fixable by configuring cross-domain measurement, but you have to know to do it, and plenty of people spend months reading distorted numbers before they notice.
Cookies behave the same way. A cookie set on the main domain is not automatically readable from the subdomain unless it was issued for the parent domain deliberately. That affects consent banners, shopping carts, and anything remembering a preference across sections. With a subfolder none of this exists: it is one origin, one set of cookies, one continuous session.
The decision, summarized
If in doubt, pick the subfolder. It is the right option for ninety percent of projects, it concentrates authority on a single domain, and it takes less maintenance.
Pick the subdomain when there is a concrete technical reason: different technology, a different resource profile, or the need to isolate content you do not control.
And if you already chose wrong and want to switch, you can, but do it properly: a permanent redirect from every old URL to its new equivalent, updated internal links, a fresh sitemap submission, and patience for a few weeks while search engines reprocess everything.
One practical note to close: check that your hosting plan allows the number of subdomains you will need, and that the certificate covers them. At BanaHosting subdomains are unlimited even on the entry plan and the certificate is issued and renewed automatically, so you can make this decision based on what suits the project rather than what the plan permits.