The first step web developers (or you) take when creating a website is choosing its domain. Primarily, it serves as your site’s name and will define its URL. When creating it, you also have the chance to add a subdomain. These are third-level domains that are part of the original top-level one.

For example, let’s say the example.com is your primary (or root) domain. Now imagine that your business expands nationally and has branches both on the west and east side. If you want to divide your root domain into more specific ones, you could add the following subdomains: east.example.com or west.example.com.

These are often useful when a business expands globally and wants to cater to foreign markets. You’ll need to add a subdomain for your site according to the language you wish to target. Subdomains are also used is by big companies who want to stratify their products.

However, if your website does not fall into any of these categories, you should stay clear of subdomains as they can hurt your SEO.

How exactly do search engines evaluate subdomains?

A common question is whether subdomains have any effect on the primary domain when it comes to ranking and indexing. Search engines, at least Google, treats subdomains as separate entities. They are able to build up on their own set of keywords and rank on their own. If you create a subdomain and target relevant words and phrases, you can rank on SERPs -regardless of your root domain’s ranking. However, this opportunity decreases as you create more and more subdomains. As a result of this, you’ll be diluting the effectiveness of keywords. Search engines treat subdomains as separate entities. So, yes, both your primary domain and subdomains can rank high, but separately.

Another aspect to keep in mind is backlink dilution. Similar to keywords, your subdomain can have its own link building strategy. Backlinks can also be added to increase its authority and visibility among the SERPs. However, if a subdomain gets a backlink, this will not enrich your root domain’s authority.