What are subdomains and subfolders?
Subdomains and subfolders are two ways to structure a website when you want to organize your content. A subdomain functions as a separate section that precedes the main domain and is separated from it by a period. You typically use it for a separate function, such as a blog, an online store, or a support section. In principle, a subdomain can function as a standalone website because it can be hosted separately and have its own technical settings.
Conversely, a subfolder is part of the main domain’s structure. It is placed after the domain name and separated by a slash. In practice, it is simply a folder within the domain’s file structure, and it inherits the domain’s authority, technical setup, and Analytics data. Subfolders are most commonly used when the content is closely related to the main site—for example, domæne.dk/viden/ or domæne.dk/blog/.
In other words: subdomains create separate sections, while subfolders group content under the same main domain. This choice affects the technical structure, SEO, and the way users navigate the site.
How do you use subdomains and subfolders?
You can use subdomains when you need to isolate parts of your website, either technically or organizationally. For example, you might want to run an online store with its own backend or an enhanced design without changing the entire main site. Because subdomains can be hosted on separate servers, you can assign different teams responsibility for each section—for example, marketing on the main site and development on a technical subdomain.
Subfolders, on the other hand, provide a cohesive structure. They’re ideal when you want your entire website to appear as a single, unified whole—both to users and to search engines. In a CMS like WordPress, you typically create subfolders automatically when you create new pages or categories. This means you can quickly build a deep information architecture without having to change any server settings.
In practice, both SEO and user experience play a role in your decision. Subdomains often require separate tracking and optimization in Google Analytics and Search Console, while subfolders are automatically shared within the same account. If you’re working on SEO strategy at an agency, you may therefore want to consider how this structure affects authority distribution and link structure.
That's why you should use subdomains and subfolders
When you organize a website, it’s not just about clarity. Your structure affects both search engine visibility and technical performance. Subdirectories are often preferable for SEO because search engines perceive them as part of the main domain and therefore assign them the same authority. This means that new pages can rank faster because the main domain has already built up trust and links.
Subdomains do have their advantages, however. They give you the flexibility to test new designs, features, or campaigns without risking any negative impact on the main site. As part of a broader digital strategy, for example, you can use subdomains to target different geographic markets with local language versions. This makes setup easier than launching entirely new domains and provides better control over traffic and communication.
Regardless of your choice, a well-defined structure provides a better foundation for both SEO and paid advertising. When working with Google Ads, for example, you can use subfolders to segment landing pages by campaign type, allowing you to measure performance more accurately. At the same time, a clear hierarchical structure helps social media and external links point accurately to the right pages on your site.
What types and varieties are available?
You can think of subdomains as separate entities with their own addresses. Typical examples include:
shop.domain.dk
support.domain.dk
Each of them can function independently, but still be associated with your brand. “www” is actually also a classic subdomain, although most people no longer consider it a separate domain.
Subfolders are often used for categories, campaigns, or information structures. They might look like this:
domæne.dk/produkter/
domæne.dk/om-os/
They can be created manually or through your CMS. The main difference is that subdirectories always maintain a connection to the main domain, both technically and in terms of SEO.
How do you use subdomains and subfolders in practice?
In practice, it comes down to choosing the solution that best aligns with your overall strategy. If you’re planning a global site with multiple languages, subdomains such as en.your-site.dk and fr.domain.dk can make sense because you can host them close to local users and optimize them technically for each market. However, if your focus is on concentrating all authority within a single website, you should opt for language structures using subdirectories instead, such as domæne.dk/de/ and domæne.dk/fr/.
You can create subdomains through your web host’s DNS settings or control panel. There, you specify which server or folder the subdomain should point to. Subfolders simply require you to create a new folder on the server or a subpage in the CMS. Most hosting providers offer tools that make both of these tasks free and relatively simple.
When measuring performance, you can integrate each section into Google Analytics or similar tools, but keep in mind that subdomains do not automatically share data. Therefore, you should carefully configure tracking methods and internal links—especially if you’re working with SEO and performance marketing across multiple websites. This ensures that you can view the entire customer journey without any gaps in the data.
What should you keep in mind?
Before you decide whether to use subdomains or subfolders, you should assess your technical resources and your goals. Subdomains often require more setup because each domain must have its own configuration, SSL certificate, and tracking. This provides flexibility, but it also creates more opportunities for things to go wrong. Subdirectories are simpler, but require you to think through navigation and structure from the start so that pages don’t get buried in too many layers.
You should also consider how your choice of structure affects your link-building strategy. Links to subdomains are not automatically passed on to the main domain, whereas links to subfolders strengthen the entire site as a whole. If you’re involved in content marketing, it may therefore be beneficial to place your blog and knowledge content in subfolders rather than on separate subdomains.
Finally, you should consider the future: does your site need to be scalable, easy to expand, and SEO-friendly? If so, a well-organized folder structure typically provides the most value in the long run. But if you frequently run separate campaigns, landing pages, or microsites with unique designs and tracking, subdomains may be the most flexible solution.
