The debate regarding subdomains otherwise known as subdirectories and which is better for SEO has been going on for years with high-profile advocates on both sides.

In 2018, John Mueller stated that subdomains and subdirectories/subfolders are treated the same in Google search, in his follow up Mueller recommends only using a subdomain when it has something different to offer compared to the rest of the site.

The full video of John Mueller’s response can be found here

While this may be true, understanding the pros and cons of each will help you make an informed decision for your website.

What is a Subdomain?

A subdomain is additional information added to the beginning of a website’s domain name. The most popular of these is “www.”

A subdomain is designed to allow websites to separate and organise content around a specific function such as separating an ecommerce function by creating “shop.” as a subdomain.

A domain name is typically made up of two parts

TLD or Top Level Domain which is the extension eg .com .net .org

SLD or Second Level Domain which is often a business or brand name

The subdomain would be the piece of information which occurs before the brand name for example the SLD below would be ReflectDigital while the CCTLD (Country Code TLD) would be .co.uk

If for example, ReflectDigital decided to launch a shop on a subdomain it might look like this

In this example

Subdomain would be represented by Shop.

SLD would be represented by ReflectDigital

CCTLD would be .co.uk

These types of subdomains are typically used when the subdomain offers something different in terms of functionality or content. A few examples of this are included below

An ecommerce or shop function where the style of the ecommerce store needs to have a different look and feel or user experience than the main site.
A blog where the main site discusses product lines and services but the blog focuses on niche relevant content and may steer away from the sites main focus, for example blog.hubspot.com
A language or region specific subdomain where different languages and or regions represent differences in content and regional nuances, for example en.wikipedia.org

What is a Subdirectory or Subfolder?

A subdirectory or subfolder comes directly after the root directory or domain name. In the example below we’re outlining a subdirectory for an example shop on ReflectDigital.co.uk

SLD would be represented by ReflectDigital
CCTLD would be .co.uk
/shop would be the subdirectory / subfolder and could contain all files relating to the shop

It’s worth bearing in mind that subdirectories can be nested. Each folder can contain another folder or folders to help group content or create categories.

For example, the /shop subdirectory above could also contain a subfolder called merchandise. The structure would therefore become

We can continue nesting folders potentially to thousands of folders deep. Too many subfolders however can make it difficult for search engines to crawl and understand the site structure and relationships between pages. Large numbers of subdirectories can also become a difficult prospect for users as URL strings become longer and more confusing.

SEO Considerations when choosing Subdomains or Subdirectories

When it comes to SEO considerations, both Subdomains and Subdirectories have their own advantages and disadvantages. We have listed some of these below for consideration

Subdomains:

Separate Entity: Search engines treat subdomains as separate entities. This can lead to issues when internally linking, maintaining security and passing authority between entities.
Increased indexing and ranking opportunities where content has a different intent to the main site for example blog.hubspot.com which contains blog posts and articles where the main site talks about a specific product line.
Branding: Subdomains can be used to create separate brands or product lines, helping to establish a distinct identity eg https://wornwear.patagonia.com/ which allows users to trade in old gear. The use of different layouts, branding and templating is made easier with the use of a subdomain which can be created as a separate site.
Separation of intents several websites use subdomains to separate out content or functionality with different intents such as recipes, shopping or language and region targeting.for example https://careers.bbc.co.uk/
Security: Subdomains can have their own SSL certificates, providing enhanced security for sensitive data.
Staging environments Subdomains can also be utilised for staging or development environments enabling you to test new designs or features prior to going live or when completely redesigning the site and undergoing an SEO migration
Confusion using too many subdomains with differing brand identities can become confusing for users and can make the site difficult to navigate.

Subdirectories or Subfolders:

Same entity subdirectories are considered part of the same website or same entity. This makes consolidation of authority, maintaining technology and internal linking easier as search engines are better able to understand the relationship between subdirectories and other pages on the site.
Comprehensive coverage of a topic on a single website can generate more authority, making it easier to rank in the SERPS
Cross selling or Overlap between sections by having all the information within effectively on site both search engines and users can understand the full picture regarding your sites offering
Clear User Journey due to the consistency across the site and the association between the folder structure and domain, a simpler user journey can be provided for the site as a whole

Best SEO Practices

As we’ve discussed above both subdomains and subdirectories have their own advantages and disadvantages, however regardless of which one we choose there are some best practices to follow in regard to SEO.

Clear Structure: Ensure that your website has a clear and logical structure, regardless of whether you use subdomains or subfolders.
Consistent Branding: Maintain consistent branding across all subdomains or subfolders to avoid confusing users.
Optimise Content: Optimise your content for relevant keywords and ensure that it's high-quality and informative.
Internal Linking: Build a strong internal linking structure to help search engines understand the relationship between pages.
Mobile Optimisation: Make sure your website is mobile-friendly, as mobile search has become increasingly important.
User Testing: Conduct user testing to gather feedback on your website's navigation and usability.

Which is Best for SEO?

While both subdirectories and subdomains have their merits, subfolders (or subdirectories) often offer advantages in terms of SEO, user experience, and technical management.

SEO Benefits of Subdirectories

Consolidated Authority: Search engines tend to view subdirectories as part of the same website. This means that the authority and link equity of the main domain can be more easily distributed to pages and subdirectories, potentially boosting their rankings.
Improved Indexing: Subdirectories are often indexed more efficiently by search engines as there is a clearer relationship between pages and they are seen as part of the main website's structure. This can lead to faster and more comprehensive indexing of your content.
Canonicalisation: Using canonical tags can help prevent duplicate content issues between the main domain and subdirectories. This ensures that search engines understand which version of the content is the preferred one. The use of canonical tags can be difficult between subdomains as effectively you instruct the search engine to index the page containing the canonical as part of a different site, whereas with subfolders it’s much more simple.

User Experience Benefits

Simplified Navigation: Subdirectories offer a more streamlined and intuitive navigation structure for users. They are often easier to understand and navigate compared to subdomains, which can be perceived as separate entities.
Brand Consistency: Subdirectories maintain a consistent brand identity throughout the website, as they are part of the same URL structure. This can help to reinforce your brand and improve user recognition.

Technical Benefits

Easier Management: Subdirectories are generally easier to manage from a technical standpoint. They require fewer configuration changes and can be integrated more seamlessly into your website's content management system.
Security: Subdirectories inherit the security measures of the main domain, providing a more unified environment for your website.

Subdirectory Best Use Cases

Internal Organisation: If you want to organise your website's content into logical categories or sections, subdirectories can provide a clear and structured approach.
SEO Focus: If you prioritise SEO and want to consolidate authority and improve rankings for your main domain, subdirectories can be a beneficial choice.
User Experience: If you want to create a simple and intuitive navigation experience for your users, subdirectories can be a good option.

Conclusion

In conclusion, subdomains can be useful in situations where you may need to create different functionality, branding or separate intent within the site. This is primarily because you are setting up an independent property. From an SEO perspective however, this separation can make it difficult to pass authority.

Given how important authority is to a site's ability to rank and the cost implications regarding link building as a whole it's often more cost effective to choose subdirectories. This ensures the quality and authority you have as a site are all contained within a single property.

Every situation is different, so if you need advice on subdomain or subfolder setup, contact us to see how we can help.

MEET THE
AUTHOR.

CARL POXON

Carl spends his days helping our clients elevate their brands through the power of SEO. From creating strategies designed to deliver excellence and meet objectives, to implementing campaigns that deliver next-level results, Carl loves it all.

More about Carl