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When to Use Subdomains and Subdirectories

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What is a Subdomain?
A subdomain is a division or alias of your domain that can be used to organize your existing website into a separate site. Typically, subdomains are used if there is content that is distinct from the rest of the site. Subdomains are indicated by the section to the left of the root URL. For instance, blog.examplesite.com and shop.examplesite.com are subdomains of www.examplesite.com.

Since subdomains are used to house sections of your site that are completely different than the scope of your main site, one of the reasons businesses use subdomains is because they need different servers and software to run these separate sections of their site. If your site has an international audience, separate subdomains allow for variations in content and language specific to the geographic region, but all versions are linked together under the main site.

Advantages of Subdomains

  1. Search engines see subdomains as unique websites unrelated to the main domain.  This could have the potential to allow subdomains you create to appear along your parent domain in search engine results pages (SERPs), pushing your competition further down in results, enhancing your authority for your product or service
  2. Subdomains can be used to target a specific market segment, reading group, or country
  3. The ability to utilize a keyword for clarity, search engine, and promotional purposes. When you use google maps, the url is formatted maps.google.com which describes it’s exact purpose.
  4. When used correctly, if a subdomain is created for an already existing site that ranks well, the subdomain will be indexed quickly and benefit from the main domain’s good standing.

A Disadvantage of Subdomains

Search Engines viewing Subdomains as Separate Domains. Sure, the traffic on your main site is humming along, and you’ve naturally accumulated a large amount of quality backlinks. When you establish a new subdomain, you’ll need to begin acquiring high quality backlinks that are separate from your main site. If your plan is to use separate subdomains, prepare to develop unique SEO strategies for each.

What is a Subdirectory?
A subdirectory is the part of the url that houses a specific subset of content. A website is like a filing cabinet, the folders within the cabinet would be the subdirectories of your site. Individual directories are located to the right of the domain. Example: www.examplesite.com/blog or www.examplesite.com/shop

When creating your site, subdirectories are the most straightforward way to organize related pieces of content on your site. Assets such as images or downloads would be in their own subdirectories. Or if you have an About section, there could be a folder for About, and then the pages for each person on your team would be in the about folder: www.examplesite.com/about/johndoe.html .

Advantages of Subdirectories
Using subdirectories over subdomains has several advantages when looked at for SEO purposes:

  1. Instead of competing with yourself with a subdomain that may have fresher content than your main domain, your focus could be on making a single website optimized.
  2. Your site could get crawled more often as you are constantly adding content and blog posts; because of this, the SEO authority that you have will be inherited by your  primary site.
  3. If you have a blog post focusing on new features or products, your users can easily go between your blog and your product/service pages.
  4. Finally, if you are tracking your site’s performance in a platform such as Google Analytics, the data is consolidated for the entire site, rather than having to look at two data points as a result of using two domains.

A Disadvantage of Subdirectories

A potential high number of URLs. Since authority is shared across all pages, the more pages there are, the more diluted authority can get. When content in a subdirectory is not as impactful as your main content, using a subdomain could be ideal.

Which is method is preferred?
This is a somewhat debated issue, however subdirectories are generally the preferred method, Every website is different and the question of subdirectory vs subdomain should be made on a case by case basis.

To get some further insights, check out these discussion threads on Moz.com

An easy way to differentiate the two is that a subdomain is a separate site altogether from your main site while a subdirectory is a label for describing the theme or meaning of a page or group of pages on your site.  Truthfully, either approach if technically executed correctly can be successful. Rather than spending too much time on which approach will give you the most results and conversions, the focus should stay on creating and maintaining a structure that makes sense for your content.

Updated: Apr 23, 2020

Since the original edition of this post, we received a number of comments asking follow up questions. The following content is intended to address the most popular questions and provide some deeper insight into the advantages and disadvantages of subdomains and subdirectories.

International SEO and its Impact on Subdomains and Subdirectories

International websites have three choices, subdomains, subdirectories, and country code Top Level Domain or ccTLD. An example of a ccTLD would be website.co.uk, which would be specific to the United Kingdom. ccTLDs are specific to countries, not languages, and are always two letters. By comparison, generic Top Level Domains or gTLDs are three letters, such as .com or .org. The ccTLD for the United States is .us, but it not often used.

By using a ccTLD, you are telling search engines that the intended audience for your site if intended to be from a specific country. Google has stated that they use ccTLDs to determine target audiences. ccTLDs are an ideal option for a business that:

  • Are well established global brand continuously creating content
  • Have physical locations across multiple locations
  • Have the resources (budget) to create and maintain a unique site for each specific country
  • Hosts a wide variety of products or services depending on geographic location
  • Are aiming to host international versions of their sites on servers potentially not located in targeted countries.

Trust is a huge factor for users on sites using their country’s ccTLD, which leads to a better user experience overall. There are some considerations:

  • Resources to build and maintain multiple versions of the site
  • Certain ccTLDs may have restrictions
  • Each site will require an individualized SEO strategy. Separate keyword research, link building, and content strategies will need to be developed for each separate site.

Using subdomains could be an option for companies that have yet to build strong international awareness and don’t have the capacity to create content filling multiple ccTLD sites. If this route is to be explored, use Search Console to geotarget each subdomain. This tactic can be used for ccTLDs, but search engines already recognize country codes as indicators to target specific regions. Subdomains are not free from effort and will require the resources to establish and maintain each separate subdomain.

You can probably determine how subdirectories factor in as an option. Using one gTLD, content can be stored in separate folders for each country or language. Since all folders are on the TLD, any link authority you’ve previously gained can be used in your favor. Using Search Console, you can geo-target each folder. Subdirectories are ideal if you don’t have the resources for ccTLDs or subdomains for every country and language you’re targeting. Subdirectories are not as strong of a signal to search engines as ccTLDs. If your efforts to geotarget sites in the same language, you could accidentally rank the wrong version.

URL parameters is another option that you could pursue. While possible to set up your site using URL parameters to determine language or region, there are no benefits and even more flaws to work through; Geotargeting with Search Console is not possible, separating visitors based on parameters is time-consuming, and with well-structured URLs being critical to SEO, a confusing URL is a benefit only to your competitors.

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9 Comments

  • Do sub domains and sub folders can make any impact on the root domain? I mean, anything badly affecting the sub domains and sub folders will affect the root domain too. Please advise.

    Reply
  • Good question! You’re likely going to see a more significant impact (relative to the root domain) from a subfolder than a subdomain.

    Google has historically said subdomains are treated as separate sites, so while there is a relationship between root domain and subdomain, the subdirectory (example.com/subfolder) will be considered to be a part of the root “website.” Any positive/negative signals coming from your subdirectory will count against the root “website.”

    Hope this helps!

    Reply
  • hey,

    Recently, and also couple of times earlier, if I’m not mistaken, Google has said that it ranks webpages and not websites. Doesn’t this effectively mean that it really shouldn’t matter which way one goes? Cause by way of this logic, blog.sitename.com and sitename.com/blog have exactly the same impact, or no impact, on any other subdirectory or subdomain of your site.

    Would love to know your thoughts on it.

    Cheers,
    Santosh

    Reply
    • Santosh – thanks for the input. It can definitely get a little tricky, especially if you’re thinking about it from the viewpoint of a singular webpage.

      I’m going to approach this purely from a content standpoint. I like to think of this more from a “content gap” viewpoint. Google historically has said it treats a subdomain as a separate website eligible for search results. If a website splits its topical relevancy (i.e. it has loads of content around a topic) between its main website and a blog website, Google says it treats the two sites as being unique websites.

      If our content is “split” between two websites, we’re somewhat diluting our “topical relevancy” between two sites — instead, we can make sure all of the content is contained within the same website. This helps users – and Google – learn that this site is an expert on a given topic because it fulfills the “content gap” (as opposed to fulfilling part of the gap on Site A and part on site B).

      And obviously there are additional items like backlinks, technical considerations, etc. that all factor into it as well.

      Hope this helps!

      Reply
  • Hi,
    We already have a domain shop running on Shopify but our domain is registered with IONOS our website is purely for sales of paper but we are about to offer printing services as well, would it be an advantage to use a subdomain or just add the printing services to the existing website?

    Thanks in advance

    Reply
    • Hi David –

      Because the two are related and you likely have overlap in users who might be interested in ecommerce and the printing services, I might consider just adding the Printing Services to the existing domain. Of course, you have a better understanding of your audience! But I’d imagine there’s quite a bit of overlap there.

      It’s mentioned in the article, but I’d really consider a subdomain if you’re looking at a radically different market segment. Otherwise, I tend to recommend a subdirectory.

      Hope this helps!

      Reply
  • Great article and very helpful. I have two scenarios that we are trying to figure out regarding subdomains vs sub directories.

    First is the documentation for our SAAS product. It is quite extensive and we’re in the process of redesigning it. Would it be better to have software documentation on a subdomain or a subdirectory? I’ve seen it on both but not sure what is best.

    The second scenario is that we are expanding our product to target certain industries. For example, municipalities and self-storage businesses. They will all use our core product but there are specific features we’re building as add-ons for those industries. We’re wondering if it would be better to have marketing content for those industries as separate subdomains or as sub directories.

    Thank you for any help you can provide.

    Reply
    • Hi Eric –

      I think I’d be comfortable hosting the documentation on either a subdirectory OR a subdomain. If you already have a customer support subdomain, it might make more sense to use that environment. But due to the nature of the content you’re suggesting, I don’t think it makes a significant difference either way.

      As for the second scenario, I’d likely recommend a subdirectory from your existing website. If the intent is the same (to promote your products) but just market to a different industry, you’ll likely want that content/information on your existing domain as opposed to a separate website.

      Cheers!

      Reply

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