What is a Subdomain? A simple explanation

Terms such as domain, subdomain, and URL are frequently encountered on the internet. People who are less tech-savvy often find these terms confusing and wonder what the difference is between them.

In this article, we will examine what a subdomain is, why it can be important, and what the difference is between a domain, subdomain, and URL.

What is a domain compared to a Subdomain?

When we talk about subdomains, it might be helpful to talk about domains first. After all, the word subdomain implies that it is derived from domain. Most readers will probably know how the term domain is defined. Nevertheless, let’s take another look at it here using examples.

First, let’s look at what is probably the most famous domain on the internet:

google.com

That is a domain. The address https://www.google.com/, on the other hand, is a URL (Uniform Resource Locator). It contains the name of the domain. Additions such as https://, www, or whatever comes after the slash (/) are not part of the domain. Strictly speaking, however, www (which is often omitted nowadays) is a subdomain.

Of course, google.com is not the only domain owned by that company. Google is active in many countries, and depending on the country, the address has a different ending. Examples are:

• google.es (Spain)
• google.de (Germany)
• google.co.jp (Japan)

Are these pages subdomains? No, these are not subdomains, but additional domains. Google owns all of these domains, but each one is a different domain, not a subdomain.

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What is a Subdomain?

A subdomain is structured as follows: subdomain.domain.com (or another extension instead of .com). So there is an addition that precedes the domain name and is separated from it by a dot.

Let’s take another look at the example of Google. As we already know, the main domain is google.com. Examples of Google subdomains are:

• books.google.com
• adsense.google.com
• analytics.google.com

In this case, we can therefore distinguish as follows:

• Domain: google.com
• URL: https://www.google.com
• Subdomain: books.google.com

If we take another look at the difference between domains and subdomains, Wikipedia is an interesting example. Wikipedia’s domain is wikipedia.org. Above, we saw that Google always has separate domains for individual countries, such as .com, .de, .fr, and .co.jp.

Wikipedia, on the other hand, resolves the different pages for different countries via subdomains. Dutch users, for example, use nl.wikipedia.org, and Japanese users visit ja.wikipedia.org. From the structure, we can see that these are all subdomains.

Subdomain vs. Subdirectory

Another way to differentiate is to use a subdirectory on the website. This is separated within the URL after the domain with a slash (/). Let’s assume that you have a website and now want to add a blog to it. You now have two options:

• blog.yourdomain.com (Subdomain)
• yourdomain.com/blog (Subdirectory)

As this example shows, subdomains and subdirectories can often be used for the same purpose. It is then a matter of preference which of the two you want to use. Further down in the text, we will look at the advantages and disadvantages of subdomains.

Examples of Subdomain usage

We now know what subdomains are and how they differ from domains and subdirectories. But why are they used now, and why should I concern myself with them? It depends on what kind of website you have and what you want to achieve with it.

Let’s look at a few examples of subdomains. We have already seen the first two in this text:

• Different languages:
  We saw this with the Wikipedia example. If you want to offer content in different languages on your website, you can follow Wikipedia’s example and use subdomains for this purpose.

  Example: en.yourdomain.com, fr.yourdomain.com, nl.yourdomain.com

• Blog:
  We have already seen this example above in the section on subdomains vs. subdirectories. If you want to add a blog to your website, you can do so using a subdomain.

  Example: blog.yourdomain.com

• Shop/Store:
  If you have an online shop on your website, but it is not the unique selling point of the site, a subdomain is also a good solution here.

  Example: shop.yourdomain.com, store.yourdomain.com

• Internet-Forum:
  If your website should include a forum where users can exchange ideas.

  Example: forum.yourdomain.com, board.yourdomain.com, community.yourdomain.com

• Mobile Version:
  Some websites also set up subdomains for users with mobile devices such as smartphones or tablets. To do this, they usually simply add an “m” (for mobile) to the front of the domain name. Ensuring that the website displays well on different screen sizes is an important factor in SEO. However, most websites do not use a subdomain to achieve this.

  Example: m.yourdomain.com

Subdirectories can of course also be used for the above examples, for example yourdomain.com/shop or yourdomain.com/nl.

Advantages of Subdomains

Subdomains can have both advantages and disadvantages, as we will see below. It depends on the motivation behind them and how they are implemented. With the right approach, we can consider the following points to be advantages.

• Can give the website a clearer structure
  If your website has a lot of content covering many different areas, subdomains often provide a clearer overview. We have seen examples of different areas above. For example, it may make sense to separate an online shop from the other content on the site (unless the online shop itself is the main page).
• No additional costs
  If you own and pay for the domain, you can usually add subdomains for this domain free of charge. If you were to apply for a completely new domain instead, this would incur additional costs.
• Individual focus on different user groups
  If you have different customers and users, a subdomain can be useful for specializing entirely in a specific user group within that subdomain. This can apply to different users from different countries, among other things.

Can a Subdomain also have disadvantages?

If you do it right, not much can go wrong with a subdomain. Nevertheless, there are a few potential disadvantages to be aware of, which I will briefly list here.

• Increased time investment
  If you use a content management system (CMS) such as WordPress, a subdirectory is easier. The same settings (themes, plugins, etc.) apply to the subdirectories as to the main page. With a subdomain, you have to adjust the settings for each subdomain again. For example, you have to select the same theme for each individual subdomain (if you want the subdomains to look like the main domain) and download and configure the same plugins again.
• Potentially increased SEO requirements
  Google considers each subdomain to be a separate entity. This means that, under certain circumstances, a separate SEO strategy may need to be developed for each subdomain, which also takes time. You should also take extra care to avoid duplicate content.
• It can become confusing once it reaches a certain size
  You should always consider carefully whether a new subdomain is really necessary. If there is a clear separation in terms of content, a subdomain can be useful. However, if you create a new subdomain for every minor topic, it will eventually become very confusing for both you and your users.

Let’s take the example of an online shop selling sweets. You don’t need a separate subdomain for chocolate, gummy bears, cookies, and many other items. A subdirectory for such categories is more suitable and clearer.

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Conclusion

A subdomain can be a very valuable tool for anyone who wants to give their website more structure and clarity. It can make work much easier, especially for large websites with a lot of content and different areas or customers.

However, if used incorrectly, a subdomain can also have disadvantages, and in some cases, a subdirectory is the better solution. Before making this decision, you should think carefully about the purpose of the website. To do this, you first need to know what a subdomain is and how it differs from other variants.