The information architecture of your website plays a key role in how Google and other search engines are able to index your site’s content. In SEO, one of the ways we organize the information on a particular site is through URL structure.
Subdomains and subdirectories are the most widely-used methods for making the core structure of a website more SEO-friendly. Knowing which structure is best for your website can be tricky, but there are key differences between the two that can help make your decision easier.
In this post, we’ll take a look at what subdomains and subdirectories are, as well as the pros and cons behind each method so you can make a more informed decision about which one makes sense for your site.
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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.
Benefits of Subdomains
- Search engines see subdomains as unique websites unrelated to the main domain. This could have the potential to allow subdomains you create to appear alongside your parent domain in search engine results pages (SERPs), pushing your competition further down in results, and enhancing your authority for your product or service. Google also won’t show the same domain twice in the same SERP in most cases, so a subdomain can be a handy workaround to that restriction.
- Subdomains can be used to target a specific market segment, reading group, or country.
- Google often gives ranking preference to sites with strong topical authority within a targeted niche.
- The ability to utilize a keyword for clarity, search engine optimization, and promotional purposes. When you use Google Maps, the URL is formatted maps.google.com which describes its exact purpose.
- 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
The main disadvantage when it comes to using a subdomain is that search engines, like Google, view subdomains as separate domains. This can become problematic when it comes to the amount of off-page authority metrics you’ve built up for your primary domain, such as backlinks.
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, like 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 .
Benefits of Subdirectories
Using subdirectories over subdomains has several advantages when looked at for SEO purposes:
- 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.
- 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 consolidated by your primary site.
- It’s much easier for users to navigate through the different subdirectories on your site, rather than hopping back and forth between your main site and a subdomain.
- 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.
- 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
If you plan to prioritize a subdirectory setup for your website, be ready to manage the high number of URLs that come with it.
Since authority is shared across all pages, the more pages there are, the more diluted authority can get. If the content in your different subdirectories isn’t as useful as the content in your top-level subfolders, then this can negatively impact your site’s authority.
If you find that the content hidden deeper in your site’s information architecture doesn’t compliment your main content well, then transferring that content to a subdomain could be ideal.
The most common example of this is when brands create a new subdomain to house all of their support content, such as HP’s support.hp.com subdomain. Instead of having that content hidden behind a wall of products and services, brands will often compartmentalize the different sections of their site – such as the support section — and move them away from the main site.
Should You Use Subdomains or Subdirectories?
This is a somewhat debated issue; however, subdirectories are generally the preferred method. Every website is different and the question of using a subdirectory versus a subdomain should be made on a case-by-case basis.
In general, we can recommend using either a subdirectory or subdomain depending on the scope of the new content as it relates to your existing content. For example:
- If you plan to continue publishing content that is topically related to what already exists on your site, then it’s recommended to use a subdirectory.
- If you plan on branching out your content and covering topics that are different than what you’ve covered in the past, then a subdomain is going to be your best bet.
To get some further insights, check out these helpful 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.
Be sure to also ask yourself these helpful questions when considering setting up a subdomain or subdirectory for your site:
- Is your brand locked into a singular topical vertical for the foreseeable future?
- Do you or your team have the resources to manage a separate subdomain(s)?
- Is your brand planning on branching out into international markets?
Updated: June 30, 2022
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 for structurally organizing content: 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 is not often used.
By using a ccTLD, you are telling search engines that the intended audience for your site is 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 are 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.
- With well-structured URLs being critical to SEO, a confusing URL is a benefit only to your competitors.