Newcomers to SEO might be surprised to find that the structure of your website has a huge impact on how your website is ranked.
It’s true–even though it doesn’t seem like your site layout has anything to do with digital marketing, seemingly basic choices about how your site is designed will be reflected in your performance in the search engine results pages (SERPs).
Here, we’re breaking down an essential question: when it comes to the choice of subdomain vs subfolder, which is better for your SEO? We’ll cover why your site structure is so important to your SEO strategy, the basics you need to understand about subdomains and subfolders, and, finally, which is better for your SEO.
First things first: let’s talk about why your site structure is so important for your SEO strategy.
A clear site structure is important for two key reasons:
If you know a thing or two about SEO, then you know that Google and other search engines use web crawlers as their tool to figure out how to rank you.
Web crawlers go through a site and follow links in the site to other public web pages, similar to how a human searcher would jump from one page to the next. As they do this, they send data on key signals (ranking factors) to Google’s servers, which is organized in the Google Search index.
The Google Search index is like the index at the back of a textbook. There’s an entry for every word seen on every webpage that’s been indexed. When a page is indexed, it’s indexed under every word the page contains.
The order that sites appear in SERPs is dictated by their order in the Search index, which is, in turn, dictated by how the site performs based on the algorithm’s ranking factors.
Google uses this index to expedite the search process. Instead of crawling billions of pages every time someone does a search, it can use the index entries.
So, what does all of this have to do with your site structure?
Crawlers go through a page just like a human searcher would, using the site structure as a navigation tool. In doing so, search engines can categorize what content is most important and relevant.
Basically, the better your site structure, the easier it is for Google to understand. And the better Google can understand your site, the more likely it is that you’ll be indexed properly.
If you’re indexed properly, there’s a better chance that your SEO campaign will work in your favour. And that means you have a better chance of increased web traffic.
How does all of this relate to subdomains and subfolders?
Subdomains and subfolders are both ways of organizing your website, making it easier for Google to index you. The good news is that they accomplish similar goals, so the uninitiated could believe that it doesn’t matter which one you choose for your website.
Here’s the problem: your choice of a subdomain vs. a subfolder has a real impact on your SEO.
So, how do you choose which one is right for your site?
First, let’s take a closer look at what subdomains and subfolders actually are.
A subdomain is a domain that’s part of a larger domain under the Domain Name System hierarchy (thus, the title subdomain).
So, what does that mean in plain English?
Basically, a subdomain is a portion of a website that acts almost entirely independently from the main site. Don’t confuse it with a domain extension, which is still part of your website. A subdomain is a whole different site, but it’s still under the umbrella of your main site.
Once upon a time, subdomains were used when a portion of a website needed a separate server from the rest of the site (remember, server space was scarce and expensive in Ye Olden Days of the Internet).
These days, subdomains are primarily used when a portion of a site has content that’s distinct from the rest of the website.
So, why would you want to use a subdomain? Wouldn’t it make sense to keep all of your sites together so the SEO can work as one cohesive unit?
That depends on the situation.
You see, in the eyes of a search engine, subdomains are treated as a different site altogether in the SERPs. Can you think of a scenario where that might be helpful?
Like, say, pushing your competition further down the results with multiple entries coming back to your site?
Plus, if your subdomain is designed properly and your site already ranks well, your subdomain can benefit from your main site’s good standing. Web crawlers would index it faster and higher.
This makes subdomains a great tool for targeting a specific marketing group. In particular, subdomains are good for audience segmentation.
With that in mind, let’s talk about subfolders or subdirectories.
Think of your website as a digital filing cabinet. Each page of content on your site is a page filed in that cabinet.
Those pages are organized by subject into folders–the subfolders or subdirectories of your site.
In fact, you use subfolders all the time. You just don’t think about it.
You can see a subfolder right in your website URL. It can look like any of these:
As you can guess, most websites use subfolders on a regular basis, as they’re the single easiest way to organize the content on your site into manageable sections for users and web crawlers.
Usually, subfolders are pretty self-explanatory–they’re organized by topic. You can even have subfolders within subfolders. For example:
Anytime you organize your site content by type, requiring you to go to a new page, you’re probably opening a subfolder.
So, why would you want to use subfolders?
There are a few important advantages to using subfolders.
First, subfolders allow you to focus all of your optimizing energy in one place. That way, you don’t have to worry about competing with yourself in the SERPs.
And because you’re adding content in the same place, you’re more likely to boost your SEO score in one location instead of diluting your efforts. This also means that your site visitors won’t have to switch between two different sites to get information.
With that in mind, let’s look at a few situations where you would want to use a subdomain over a subfolder.
Let’s say you want to run a blog in addition to your main website. Companies opt to do this for a variety of reasons, often because they want to create a distinction between the blog and the rest of their content.
If that blog is meant to be a content workhorse in its own right, it may be a good idea to use a subdomain instead of a subfolder. This will allow you to rank your blog separately from your main site, so your blog could get readers you may not have gotten otherwise.
Let’s say you’re a company that serves many different regions or countries. For example, let’s say you serve Ireland and France.
There’s an obvious problem here: the language barrier.
In order to make your site accessible, and to make sure your site is properly represented to each audience, you may want to create a subdomain serving a different region, catering to their language and cultural differences rather than relying on Google browser translation to do it for you.
This will show your audience, regionally and globally, that you’re committed to serving them.
Or perhaps your company has subsidiaries or more than one product line. Those subsidiaries or different product lines don’t necessarily cross-pollinate very well. That’s a problem for your SEO since Google won’t be sure what to rank you for.
You can mitigate this problem with a subdomain for your different product lines or subsidiaries. That way, Google can rank them separately, without each individual component negatively impacting another unrelated component.
Basically, if there’s a clear dividing line between one topic and another, you might be best served by a subdomain.
Now, what about when you want to use a subfolder?
Let’s go back to our original example: you have a blog in addition to your original website. Now, let’s say you have 50 good backlinks on your primary domain and have managed to accrue 50 good backlinks on your blog as well.
In that case, if the blog is in a subfolder, that means you have 100 quality backlinks to your primary website. That’s fantastic news for your domain authority, which means that any page under your primary domain (including the subfolder) will rank higher.
Should you divide and conquer or find strength in numbers? Or rather, are subdomains or subfolders better for your SEO?
That depends on your strategy.
According to Google, in one of their ever-helpful, delightfully noncommittal statements, subdomains and subfolders are (officially, at least) treated equally.
And technically, this is true. Web crawlers index subdomains and subfolders exactly the same way. Which means that, technically, you have just as good a chance of getting a subfolder ranked as a subdomain.
So…it’s that easy, right? Not quite.
SEO experts disagree with Google on this front–subdomains and subfolders aren’t actually the same where SEO is concerned, and sites shouldn’t make the mistake of treating them as interchangeable.
If you know SEO, you’re probably confused. Usually, SEO experts are all about deciphering the word of the almighty Google, not contradicting it.
In this case, SEO experts and Google are both right, so to speak. It just depends on which way you look at it.
On a technical level (Google’s argument), subdomains and subfolders are indexed the same and thus are not ranked any differently. So in a way, Google is right.
SEO experts look at on-the-ground data. The reality is that while you can rank a subdomain–and you can even rank a subdomain well–there’s a catch.
Since subdomains are ranked in SERPs as a different website from your primary site, technically, your SEO is separate. That means that it’s going to take a lot more work to rank a subdomain than a subfolder since your subfolder can rank along with your primary website’s SEO strategies.
With all of that in mind, let’s get back to our original question: should you use a subdomain or a subfolder?
Ultimately, it depends on what your needs are.
If you need a section of your site to cover a totally separate aspect of your business whose external links won’t apply to the rest of the site, then it’s a good idea to use a subdomain.
If, on the other hand, you need a separate section of your site that still relates to your primary business, then you’d be best served by a subfolder.
The choice of subdomain vs subfolder illustrates an important point: designing a successful website is an undertaking. It takes time and a rigorous understanding of the problems you need to address.
It helps if you can start your website knowing you’ve got the essentials covered. That’s where we come in.
And if you need more ideas, check out our blog for more great explanations of essential SEO concepts like top-level domains.