What is a Subdomain and How Does it Affect Your Site’s SEO?

An image of NASCAR's shops homepage, used as an example of when to use subdomains.

If we look at the image above from Nascar, we’ll see they use a subdomain for their store. This makes sense if you think about the actual purpose of Nascar.com when compared to a Nascar-related e-commerce store.

When navigating the internet you may notice the URL changing as you click from site to site. Sometimes you have a simple URL like www.mysite.com. Or, you might see words added before the site like this, www.shop.mysite.com.

The word “shop” in this case, is a subdomain and it’s used to differentiate the two websites from each other.

In this guide, you’ll learn what subdomains are, how you can use them, and whether or not they impact SEO.

What Is a Subdomain?

A subdomain is an addition made to a URL string to separate and organize content on a website.

Using a subdomain allows you to partition areas of the site, such as a blog or store, from the main areas of your website.

Each time you see a URL, there are essentially three main parts:

The top-level domain of a URL.

1. Top-Level Domain or TLD: This is the extension at the end. Examples would be, .com, .org, or .io.

An image of Neil Patel's website, with an arrow pointing to the second-level domain of the URL. — The second-level domain of a URL

2. Second-Level Domain or SLD: This is the creative portion of the domain. In Neilpatel.com, Neilpatel would be the second-level domain.

An image of Neil Patel's website, with an arrow pointing to the subdomain part of the URL. — The subdomain of a URL.

3. Subdomain: The subdomain in this scenario would be anything that comes before “neilpatel.” For example, if you go to app.neilpatel.com, the “app” part of the URL is what leads you to the keyword research tool, Ubersuggest. In this case, “app” would be the subdomain and it helps separate the tool from the rest of the site.

Many sites use this to create different sections for organization and user experience purposes.

An image of a Wikipedia page. — An example of Wikipedia uses a subdomain to create different sections of their website.

If we look at the example above from Wikipedia, you’ll see they use one to differentiate the languages across their site. There are many purposes for subdomains, but they’re all used to make the experience easier and faster for the user.

Now you have an answer to “what is a subdomain.” Let’s learn how to create a subdomain.