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Subdomain or subdirectory? What are they and how they affect SEO


One of the most heated debates I have ever participated in is whether Taylor Swift is a good dancer.

The first thing you should know about me is that Taylor Swift is my favorite artist. So it is difficult for you to convince me that she is not good at anything (because she is not).

When discussing whether subdomains or subdirectories are more suitable for SEO, SEO experts may use the same approach. As a marketer, such arguments can lead to confusion and paralysis of analysis.

In this article, you will understand the difference between subdomains and subdirectories and how they affect SEO. Both have pros and cons, and you need to consider all of these factors before advancing your website project.

Subdirectory URL

In the URL, subdirectories are located after the root directory or domain name. For example, the root domain of HubSpot is hubspot.com. So the subdirectory URL may be hubspot.com/pricing. Or it may be more complicated, such as hubspot.com/pricing/sales. The following is a description of a possible subdirectory structure.

Example of HubSpot subdirectory structure

When it comes to subdirectories, think of a structure similar to nested dolls. Each folder can be built into each other almost indefinitely. This means you can include a subfolder in a subfolder within a subfolder until you are dozens or even hundreds of levels deep.

But just because you can does not mean you should.

Too many levels of subfolders can become a nightmare for SEO. The URL string becomes long and messy, every time you click to enter the next piece of content, it will bring risks to the user experience. Search engine crawlers will find it almost impossible to crawl your website to get new content, and you may win Other SEOs were added.

On the other hand, subfolders are very useful for SEO because they tie any obtained backlinks, domain authority, and page authority closely to the root domain. When the website is fairly easy to navigate, the URL will be short and simple, such as hubspot.com/careers, which means you can market specific webpages or landing pages through the URL without confusing your audience.

The structure of the subdomain is fairly flat at the top level. You will own the root directory and line up all the subdomains under it. All subdomains are at the same level. There will be no subdomains in a subdomain, just like a subfolder in a subfolder.

Example of HubSpot's subdomain structure

SEO and subdomains

Subdomain may be very suitable for SEO, but it needs a dedicated person or team who can manage it. Unlike subdirectories, the domain authority of subdomains is not automatically dropped from the main domain name. If you charge by domain name, you may also need to pay extra for tools or subscriptions, because each subdomain usually counts as a separate website. Keeping these challenges in mind, let’s take a closer look at the benefits of using subdomains.

Why use subdomains?

If your business has a lot of content that makes it difficult to manage everything on one website, subdomains are ideal. You will also find this structure useful if you run multiple large repetitive marketing campaigns that require separate landing pages, or if you plan to establish partnerships with other organizations and want to split the brand on the project.

In short, if you have a related business that needs to separate the content on your website, subdomains make sense.

There are many situations where companies should use subdomains. The following are the most common.

1. Support

Sometimes it doesn’t make sense to provide customer support on your main site. For example, Google uses support.google.com instead of google.com/support. The main reason may be the site structure. Google.com is a search engine, and Google’s support hotline is not part of its search business line. Therefore, it needs its own subdomain to properly connect and serve its users.

2. Different regions

If you serve multiple regions, whether domestic or international, using subdomains is a good idea. If you have a German site and an English site, it does not make sense to list them as subdirectories. For example, Craigslist uses subdomains for the different regions it serves. These are its two subdomain sites: orangecounty.craigslist.org/ or stgeorge.craigslist.org/.

3. Blog

Many companies choose to use their blog as a subdomain. In fact, this is what HubSpot does. If you will notice, the page you are on now is the blog.hubspot.com page. However, this particular article is located in the Marketing subdirectory of the blog.hubspot.com subdomain. Websites may choose to use their blog as a subdomain. If they have a large enough content activity, they deserve to have their own hierarchy and growth path (more on this later). In addition, if you want to create a niche authority, subdomains are useful for blogs.

4. E-commerce store

For companies that sell goods, in addition to regular products or services, they can also place e-commerce stores in subdomains. HubSpot does the same. In addition to our main software center, HubSpot products can also be purchased on shop.hubspot.com.

5. Activities

If your company hosts events, it’s best to divide this part of your website into a subdomain. Likewise, this is useful when you want to distinguish a certain part of your website from a regular product or service. Microsoft does this through its events.microsoft.com.

Technically speaking, a website can use both subdomain and subdirectory structure at the same time. A subdomain usually has at least a few subfolders to organize content, but there may not be as many subdirectories. This is because there are fewer types of content covered in subdomains than in the root domain containing subfolders.

Therefore, it is important to understand the main structure of your website. To determine this, let’s take a closer look at how subdomains and subdirectories affect SEO.

How do subdomains and subdirectories affect SEO?

Some SEO experts believe that Google’s crawlers may confuse websites whose subdomains are completely different from the main domain. However, others say that its crawler can recognize the child domain as an extension of the parent domain.

According to Google, the site crawls, indexes, and ranks subdomains and subdirectories in the same way.

In the video below, Google Webmaster Trends analyst John Mueller said that subdomains usually do not affect the ranking of the site. In fact, he said that Google is smart enough to treat your main domain and subdomains as being tied to the same website.

Some SEO professionals believe that subdomains will not share the authority gained from inbound links (or backlinks) with the root domain. The reverse is also true; since subdomains are treated as separate entities from your root domain, they may not inherit any link permissions you have built for the core website content.

In addition, if you are optimizing your pages for the same keywords on your main site and subdomains, you may be competing with yourself.

On the other hand, other SEO experts believe that subdomains can make it easier to browse your website. Ultimately, this will lead to a better user experience, which in turn will increase engagement rates and thus improve your SEO.

If you own a large company and subdomains serve different purposes and essentially operate as separate businesses, subdomains may help.

For example, Disney has several subdomains, such as cars.disney.com, shop.disney.com, and movies.disney.com.

Since these subdomains are used for very different purposes, it does not matter whether the site does not share the same authority from the backlinks, as they may not target the same keywords.

According to some SEO experts, another benefit is that subdomains can help establish niche authority. For example, you may want to treat your blog as a separate entity from your products or services.

Conversely, if your site does not have any broad verticals in navigation, then you may not need to use subdomains because you want as many links as possible to return to your main site. If you don’t have a compelling reason to use subdomains, then subdirectories will work fine.

Which is better: subdirectory or subdomain?

Although this topic is often confusing, the final decision depends on the needs of your website. If you have a lot of different but important content to share, subdomains can provide organization and structure for your site. Subdirectories are helpful for small websites without a lot of content. No matter which structure you choose, you want to keep up with SEO best practices to achieve your website goals. The free guide below will help you improve your website with the free SEO audit toolkit.

Editor’s note: This article was originally published in February 2020 and has been updated to be comprehensive.

seo audit


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