What Is a Subdomain? Definition, Examples and Setup (2024)

Building an online presence starts in a fairly straightforward manner: Simply decide how to make a website and purchase a domain name. Things get more complicated once you look into growing your site.

As you may know, a domain is the section of a URL that identifies a website. Typically, the entire infrastructure of a site lives under a domain, preferably a top-level domain (TLD) that varies per your site needs like .org vs .com TLDs. However, there are circ*mstances in which a website section becomes so expansive that it affects your user experience and site performance. In those cases, subdomains can come in handy.

This article will explain what a subdomain is, discuss subdomain examples and teach you how to create a subdomain on your own.

What is a subdomain?

A subdomain is a prefix added to a domain name to separate a section of your website. Site owners primarily use subdomains to manage extensive sections that require their own content hierarchy, such as online stores, blogs, job boards or support platforms.

Subdomains function as a separate website from its domain. This distinction enables you to develop a section of your website without muddling your site’s overall intent. Because they are distinct from the TLD, a subdomain can require additional resources for content management, technical SEO, and website infrastructure in order to be effective. But well-managed subdomains can help you increase your chances to build a niche authority, add customer value, improve SERP visibility and gain organic traffic to your brand overall.

Regardless of your purpose for creating a subdomain, optimize your subdomain name to clearly signal your standalone site’s purpose. Plus, ensure you’re working with an SSL certificate provider that provides subdomain protection.

While choosing a domain name is one of the first steps you’ll make when creating a website, you can create a subdomain at any time. Registering a domain name gives you the rights to unlimited subdomains, including anything from “abc.” to “xyz.” This list of best domain registrars will help you accomplish this.

What is a subdomain used for?

Subdomains are often used to organize a website's content into different sections. For example, a company might use a subdomain for its blog, another subdomain for its support forum and another subdomain for its online store.

Subdomains can also be used to create sub-websites that are related to the main website. For example, a university might use a subdomain for each of its campuses, or a news website might use a subdomain for each of its different sections, such as sports, business and entertainment.

Here are some of the benefits of using a subdomain:

What's the difference between a subdomain and a subdirectory?

Whereas search engines see a subdomain as separate from its domain, a subdirectory (also known as a subfolder) is a website organizational folder that nests inside a domain. Content in each folder will often share a common keyword intent but elements like the menu and navigation will be the same menus as the main site. Separating content under a subdirectory instead of a subdomain shows search engines that the content it supports sits on the root domain.

Site owners should take SEO and overall planning into consideration when deciding if a subdomain or subfolder will work best. And as technical SEO consultant Nikki Halliwell explains, "When you're creating or migrating to a new subdomain or subfolder your team should be “aware of what you're doing and why you are doing it. That includes everyone from internal stakeholders as well as the dev teams."

When is a subdirectory better than a subdomain?

If you have a complex part of your site that complements the domain as a whole, then a subdirectory could better facilitate your goals over a subdomain. Niche-relevant blogs, product listing pages, and team profile pages are all good use cases for when a subfolder could work well for a website.

For instance, a general pet adoption agency may want to create category pages in subdirectories for their cat and dog content to signal to Google that these pet adoption types are related. This makes sense for Google and users because each new folder aligns with the overall goal of the site.

When is a subdomain better than a subfolder?

You may want to consider using a subdomain instead of subfolder if you have:

For example, if a dog adoption agency was doing a special project where they were partnering with a cat adoption agency, they may want to create a subdomain dedicated specifically to that project.

Splitting content out in this way can help ensure that Google’s understanding of the core purpose of the TLD (in this case ‘dog adoption’) is less affected by content on the subdomain (in this case ‘cat adoption’).

Subdomain examples

Now that we’ve answered the question “what is a subdomain,” let’s look at a few examples of when to use a subdomain:

1. eCommerce

Due to the complexity of online stores, businesses often choose to create a separate site architecture to handle transactions. This distinction allows companies to offer different functionalities than the main site needs or has available. The store.playstation.com subdomain, for example, is a platform where users can purchase games for their consoles.

2. Mobile

Online platforms that require an overhaul to perform well on mobile devices usually host their mobile sites under dedicated subdomains. For example, Facebook crafted a distinct interface for its mobile users under m.facebook.com. The company shaped the layout to fit a mobile device’s oblong shape.

3. Location

Companies providing localized or geo-specific content can easily do so using subdomains. For example, Yahoo curates UK-related news using uk.yahoo.com and US-related news on us.yahoo.com.

4. Audience

Subdomains allow businesses to create unique sites targeting distinct audiences and even password-protect them if needed. While most Lyft users dwell in the ride.lyft.com subdomain, those interested in the company’s self-driving initiative can visit the autonomous.lyft.com subdomain.

5. Blog

Because blogs often target topics and keywords not directly related to the rest of the site, you might consider situating your blog on a subdomain. The Library of Congress massive site caters to a different audience than its blogs. So, blogs.loc.gov hosts hundreds of articles on a different interface where readers can browse and search for their desired content.

6. Support

When Frequently Asked Question pages don’t thoroughly answer all customer questions, site owners can create a dedicated support platform under a subdomain. This organization can make the platform easy to navigate and better optimized for search engines.

A quick glance at support.wix.com shows that the platform’s subdomain has a unique, carefully-designed and complex structure that addresses users in need of assistance.

7. Content

Sites that craft extensive, highly-branded content for certain subjects often choose to work with dedicated subdomains. Products, films, teams and publications with divergent content might use subdomains to distinguish their brands from the umbrella organizations.

As one would expect, the content found on The New York Times functions drastically differently from the content found on NYT Cooking (cooking.nytimes.com). Separating the content allows each brand to signal its own authority to search engines.

8. Language

Creating independent subdomains for each language enables organizations to keep their web addresses clear and cohesive. This is a common practice in international SEO. For example, Wikipedia has a separate subdomain for each language. Interestingly, the es.wikipedia.org homepage differs not only in language from the en.wikipedia.org homepage but also in content.

9. Forum

Due to the intricacy of online community building, forum creators commonly use dedicated subdomains. Take wordreference.com: the root domain stands as a bilingual dictionary. However, forum.wordreference.com is a place for users to ask questions and discuss the meaning and proper use of terms and phrases that have yet to make it into the root dictionary.

10. Function

Amazon created a subdomain for their AmazonSmile initiative. Whenever a user shops on smile.amazon.com, Amazon donates 0.5% of eligible purchases to the charity of the user’s choice.

How to create a subdomain

Before you set up your subdomain, you’ll need to register a domain name. If you already have one, follow the steps below:

What is a subdomain FAQ