What Are Subdomains and Subdirectories? Explanation of Differences, Proper Use, Impact On SEO, Etc.


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subdomains vs subdirectory

Don’t you know the difference between “subdomain” and “subdirectory” and how to use them properly?

This time, we have summarized the overview and differences between “subdomain” and “subdirectory”, how to use them properly, and the impact on SEO. Use this article as a reference to build effective sites and content.

What are subdomains and subdirectories?

“Subdomain” refers to a domain with a new character string added before the original domain. On the other hand, a “subdirectory” is a domain with a new character string added after the original domain .

The reason why we think about domains separately is that we can convey information that is easier for readers to understand. Some websites on the Internet have Japanese, English, or overseas versions.

Understand the differences and characteristics of each and use them in the optimal position on the site.

What is a subdomain?

A subdomain refers to a domain with a new string added before the original domain. Specific examples are as follows.

  • Main domain https://●●●.○○○/
  • Subdomain https://exmample.●●●.○○○/

The original domain is https://●●●.○○○/, and the character string “●●●” is preceded by “exmample.” It is characterized by clarifying the difference and trying to differentiate it from the usual original domain.

Also, you can freely decide what to put in the characters separated by slashes.

Formally, the base domain and subdomains are treated as separate sites, but since the internal links you have installed are valid, they are not evaluated as completely separate domains.

Using different pages makes it easier for readers to read, so get a subdomain if necessary.

What is a subdirectory?

A subdirectory is a domain with a new character string added behind the original domain. Enter a slash after your own base domain and add a string.

Specifically, it is as follows.

  • https://●●●.○○○/
  • https://●●●.○○○/exmample./

A comparison shows that “exmample./” was added after the final slash.

The URL of the subdirectory is usually the page for the English notation of the site. Clarify the difference so you can create content that resonates with your readers.

Also, the subdirectory has the meaning of creating a subdivided homepage. If you want pages with more detailed explanations, using subdirectories is a good way to do it.

Aim for easy-to-read content by leveraging subdirectories where appropriate.

Difference between subdomain and subdirectory

The difference between subdomains and subdirectories is

  • operating costs
  • Influence received from the main domain

And so on. Understand the difference between subdomains and subdirectories and aim for an SEO-friendly site.

Advantages of subdomains

Advantages of subdomains

  • There is a branding effect of the operator
  • no domain costs

And so on.

The subdomain has the same format as the original domain of the operator, so the advantage is that the branding effect of the operator can be obtained. Specifically, if the operating company is well known, subdomains can be used with confidence. This is because even if there are some differences in the service, the reliability of the operator has a lot to do with the readers.

On the other hand, when using the service of a subdomain with low name recognition, suspicion arises, which makes it difficult for customers to become established.

Another benefit is that there are no domain fees. Normally, it costs money to use multiple services, but with a unique domain, you can get multiple URLs just by acquiring one domain.

As a point of caution, if there is a limit on the number of subdomains, there may be cases where a fee will be charged, so let’s check in advance.

Disadvantages of subdomains

Disadvantages of subdomains

  • It may be recognized as the same page as the main domain
  • SSL certificate issuance fee required

And so on.

Subdomains may be recognized as the same page as the main domain and may not be displayed in search results. This is because, as a rule for displaying on Google, if it is recognized as a page of the same domain, it will not be displayed in the search results. Therefore, subdomains may be excluded from the display of search results.

Next, subdomains require an SSL certificate issuance fee. This is because SSL certificates play a role in preventing third parties from viewing personal information, credit card information, and information required for login on the site. Conversely, if security cannot be guaranteed, even if you acquire a subdomain, you will not be able to operate it.

Let’s use subdomains after recognizing the above two disadvantages.

Advantages of subdirectories

Benefits of subdirectories

  • Main domain reputation can be inherited directly
  • low operating costs

And so on.

Subdirectories are evaluated for the main domain used. The reason is that unlike subdomains, domains are linked, so there is an impact on existing pages.

Also, creating similar content increases the domain power of both the main domain and subdirectories in synergy.

Second, subdirectories are attractive because of their low operating costs. Because it uses the same server as the main domain, there is no need to operate it separately.

Another advantage is that there is no need to make new settings, so it is time-saving.

Subdirectories are recommended because they are highly convenient and cost can be kept low.

Disadvantages of subdirectories

Disadvantages of subdirectories

  • Potential duplicate content on your site
  • Direct impact of SEO penalties

And so on.

Subdirectories may create the same content. The reason is that it is possible to create subdivided pages, but if the amount of content increases, the content may overlap.

At first, there are few pages and the content of the article is input, so it is difficult to duplicate, but if the amount of content becomes large, it may be duplicated, so be careful.

Second, subdirectories are directly affected by SEO penalties. This is because the content will be linked, so the penalties will be affected in the same way.

Be careful not to get SEO penalties for the same content.

Read Also: What Is a Spam Site?

Select the usage of subdomains and subdirectories according to the operation method

Points for proper use in operation methods
sub domain Services related to the root domain, content with significantly different themes and roles
subdirectory Contents with similar themes and roles, information related to products

When using subdomains and subdirectories properly, it is important to choose according to the operation method. As shown in the table above, they have different characteristics and aptitudes, so it is necessary to use them properly according to the purpose.

Specifically, if the root domain introduces “ingredients”, the subdomain is “delivery”. It’s not a close theme, but I have an image of a service that is related to food ingredients and delivery (food) even if they are far away.

Subdirectories, on the other hand, are better suited for content that details specific ingredients, such as eggplant or soybeans. It is an image with high relevance in detail. In addition, subdirectories often contain information related to products.

It is important to use the above two types properly depending on what kind of information is sent.

Subdomains and subdirectories themselves have little SEO advantage

Subdomains and subdirectories have very little SEO advantage. This is because it is not about which one is superior, but that each has a role and it is important to use them properly.

In fact, Google does not treat subdomains and subdirectories very differently, and recommends a method that can be operated in the long term. If you use them properly and arrange the homepage structure, you may be able to greatly increase the domain authority.

As a concrete step, first, let’s use subdirectories to increase the domain power of the root domain. The first priority is to increase the domain power of the root domain.

On the other hand, if you start with a subdomain, it will be less efficient because the strength of domain power will be determined by the root domain. It is an efficient way to start with the content management of subdirectories and increase the domain power of the root domain.


In this article, I introduced “Proper use of subdomains and subdirectories “, ” Advantages and disadvantages “, “Advantages and disadvantages in terms of SEO “, etc.

SEO is the most effective way to create a good site for users, and it is considered the same point of view to use subdomains and subdirectories properly.

Use the points introduced in this article as a reference to improve the SEO effect of your site and homepage.