Subdomains Versus Subdirectories – Which Is Better for SEO In 2023?

The one topic we have seen Google and SEOs disagree on the most is the best place to host content – subdomains or subdirectories. SEOs say subdomains are not optimal, and Google says it does not matter because they can read and understand your content wherever it is. Google even put out a video to clarify the matter, but no one was satisfied with their answer.

So, what is the disconnect? While it is true that Google has no problem understanding content on subdomains, SEOs say that content does not perform as well in Google’s search engine. Google disagrees and says that subdomains are not a problem, yet the SEO industry continues to publish case study after case study that refutes Google’s claim.

We should host our content on our primary domains – unless we have a very good reason not to. Even if Google turns out to be correct, and it does not matter for performance, organizing your content in subdirectories on your primary domain is the better decision for your infrastructure and long-term SEO.

What is the Difference Between a Subdomain and a Subdirectory?

If you are given the choice between hosting a blog for your website at “blog.xyz.com” and “www.xyz.com/blog,” will the choice matter? Is there a big difference between putting “blog” at the beginning of a URL instead of the end?

There is a difference, but it’s subtle and goes back to the early internet.

  • Subdomain

In the early days of the web, a single server could host multiple services and they would be assigned to different subdomains. It was conventional for system administrators to host additional services on subdomains, like “mail.xyz.com” for the email server or “ftp.xyz.com” for filesystem access.

Even “www.xyz.com” is a subdomain, but we do not usually think of it that way because the service we use most of the time is the website, but it does have a purpose.

Subdomains should be used to organize services that are separate from each other but still part of the entity that owns the root domain (“domain.com”). They are still used this way, even for separating websites owned by the same brand.

  • Subdirectory (or Subfolder)

Subdirectories, also called “subfolders,” were originally for allowing users to navigate a website according to the file structure of the server hosting the website. Now, most websites store their content in a database and display it to users through a content management system, so the server’s file structure is irrelevant.

Organizing URLs like a directory as if there were a file structure is still useful because it lets users know “where” they are on a website. It also communicates to users that the content on any given URL is closely related to the subdomain they are on.

The Debate – Subdomain versus Subdirectory

The debate between using subdirectories or subdomains for organizing content is not really about what helps users understand a website. It is mostly about what will yield the most organic search traffic on Google and other search engines.

SEOs want to know if a brand’s content is split between two (or more) subdomains, will Google treat the subdomains as separate sites or a single one?

How Google deals with the situation is important. If Google treats subdomains separately, then ranking signals related to expertise, authority, and trust might not be shared between them.

  • Google’s Point of View

Google has always treated content separated by subdomains in a way that suits their needs.

As far back as 2007, Google said that they treated subdomains as separate for one aspect of ranking. However, they found that it led to people abusing how Google handled domain diversity in the SERPs.

People would like to know if separating content by subdomain will make a difference in their rankings, but Google wants us to know that Google’s needs are taken care of either way. But, they also would like us to understand that Google does not have a preference and that we should do what is easiest. We disagree with Google on both points, and we will get to why.

  • SEOs’ Point of View

SEOs want to know three things:

  1. If Google treats content organized by subdirectories differently than content separated by subdomains
  2. If there is different treatment, which systems distinguish between them and how they work
  3. Which configuration is ultimately better for rankings, traffic, and revenue

Google does not want us to know which systems do what and how because it makes them vulnerable to abuse. If the Helpful Content Update had a strong impact on rankings, many SEOs would begin testing to see if their content worked better on one domain or several, just like the domain diversity problem discussed by professionals.

Due to Google’s secrecy, the point is generally not answerable. Someone would have to pick a specific part of Google and determine how to test its reaction to using subdomains to reach a conclusion.

Many SEOs have consolidated their content into one subdomain and found their overall performance improved. Due to how many case studies have come out, it is widely believed among SEOs that using subdirectories to organize content is better than subdomains.

Taken with lots of anecdotal evidence over the years, SEOs have good reason to believe that subdirectories tend to perform better than using several subdomains.

Impact of Subdomains & Subdirectories on SEO

Deciding where to host your content is not just about what it communicates to users and the way Google treats it in its algorithms. There are also practical day-to-day SEO concerns to mull over.

  • Link Authority and Backlinks

Where would you rather host your content, on two domains with 1,000 backlinks each or one domain with 2,000 backlinks? Which setup would you rather maintain years down the line?

If you are investing in link building for content that lives on a separate subdomain, you must make sure that the subdomain redirects its URLs after it is retired. At Dwarika Web Solutions, we frequently see great backlinks pointing to forgotten legacy subdomains in clients’ broken backlinks.

Suppose there are multiple URLs on a subdomain that you need to redirect to several other URLs. In that case, the redirection is not as trivial as setting up a DNS record to blanket redirect everything to a single URL. That legacy subdomain must have a web server attached that can deal with all those specific redirects.

  • International Subdirectories

International websites are usually implemented in three ways: ccTLDs, subdirectories, and subdomains. Subdomains have no upsides over the other two options. ccTLDs aren’t optimal either, but at least they contain a strong signal about how they want to target international users.

Google’s recent update to their URL structure advice in Search Essentials does not even mention subdomains, which is curious.

Using a subdirectory strategy for international websites is something we see more brands using every year. We think they realize the benefits of having everything in one place: one CMS, one development team, better content parity, and easier manag0ement of hreflang tags.

  • Mobile Subdomains

Creating a subdomain to host the mobile version of a website is not as popular as it once was, and it is becoming rarer every day, but they are still out there.

Wikipedia is a popular example of a website that has not adopted responsive design. They also use subdomains for their international strategy, so they must maintain a mess of subdomains like en.m.wikipedia.org and fr.m.wikipedia.org.

The future of the web is responsive and mobile-first. It is the easiest and simplest way to adapt to modern internet usage. Brands that disregard this tend to tack on mobile subdomains that plague their technical teams with problems like:

a. Wasted crawl budget and canonicalization issues
b. Server-side device detection and redirect handling
c. Maintaining content parity between mobile and desktop sites
d. Shrinking content and navigation to fit mobile screens

There is no reason not to use responsive design at this point.

  • Cost

How many websites do you want to pay for? How many web applications do you want your engineers to maintain? Every subdomain you add to your website introduces another hosting environment to your technology stack and all the business concerns that come with it.

A new subdomain could mean additional costs for any of these:

a. 3rd party hosting or subscription fees
b. Additional SSL certificates or a wildcard certificate

c. Developer hours for the subdomain CMS
d. Additional colocation space or network hardware

You would also have to manage the subdomain’s login credentials, analytics, security, and webmaster consoles. These headaches add up fast if you have regulatory compliance to worry about.

When to Use a Subdomain?

There are a few cases where a subdomain makes the most sense for your brand outside of technical necessity. Usually, it is for a sub-brand or a product substantially different from what the brand normally sells.

If your content satisfies most of these criteria, then you should probably use a subdomain:

a. The content or branding is not different enough to justify an entirely different domain
b. Users would be confused if they navigated between the two content experiences
c. The content sells a completely independent product or is part of a portfolio of products

Google itself is pretty good at this. They have developers.google.com, assistant.google.com, cloud.google.com, store.google.com and the list goes on. Each subdomain is an aspect of Google but independent and hosts its own thing.

One more valid case for a subdomain is content that will never need to be indexed by a search engine. Paid landing pages, customer portals, and company intranets are all good examples.

Customer support and user community sections can stay separate. We do not think investor information, careers, and user-generated Q&A content will help the sales website rank because the content is not relevant to its KPIs.

When to Use a Subdirectory?

The best way to keep away from dealing with the subdomain question is to start with a website or CMS that does everything you want on one domain. At Dwarika Web Solutions, we often find brands that try to tack on the functionality later because they do not foresee an upcoming need.

Begin with an infrastructure that will do everything you need. If you need a blog or eCommerce experience, choose a CMS with those built into the app. Or you could even use an extensible CMS, like WordPress or Drupal. Shopify has a lot of SEO quirks, but it is relatively solid and comes with a few site speed improvements out of the box.

Suppose you already have a website and do need to add functionality your existing infrastructure does not support. A few common additions brands need to make are:

a. Their blog
b. Ecommerce
c. Customer support
d. Technical documentation

Usually, the easiest way to attach these to an existing site is to host them on a separate server and map it to a subdomain. However, putting them in a subdirectory is straightforward with a reverse proxy.

A reverse proxy is a way to make other servers accessible through a subdirectory instead of a subdomain. They do a lot more, but their purpose for SEO is mostly that.

Suppose you were adding a blog to your PHP website and hosting it on WordPress. Typically, the easiest way to do this is to map blog.xyz.com to the server hosting WordPress, but given how the SEO chorus says, “use a subdirectory!” you ask your engineers to invoke a reverse proxy.

With that reverse proxy, you can host the blog at www.xyz.com/blog, and the reverse proxy will reroute all requests in the /blog subdirectory to the WordPress server instead of the PHP server.

From Google’s point of view, /blog is part of the www.xyz.com website even though that subdirectory serves content from a different server.

Google Will Keep Its Secrets

We believe the major reason Google will not give us a straight answer about how they treat subdomains is that no single person knows. For a Google spokesperson to begin to answer the question, they would need knowledge of all the parts of Google Search that “care” about subdomains, then investigate each part to see what it does.

Supposing they did that, how much could they say publicly? It is very important for Google to prevent abuse by not letting the public know too much about how its systems work.

We do not think we will ever get a satisfying answer from Google about the topic. Hopefully, they advance to the point where it does not matter how our content is organized, and case studies no longer show a preference. Until then, subdirectories are probably better for your situation.

Dwarika Web Solutions is a leading SEO company in Toronto that can help you outshine your competition in 2023 by performing the best content marketing. Feel free to contact us at +1 (855) 561-4557 to speak with a professional!


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