A subdomain is technically a part of the main website but, unlike a subfolder or subdirectory, it functions just like a completely separate domain. At least, that’s how it’s normally perceived by the search engines. This kind of website architecture has been used for years, and you’ve likely seen it quite often. For example, if you had a website on “example.com” a subdomain could be “mail.example.com” or “about.example.com.”
Subdomains are often used on various websites for different purposes. The question is: are they effective and should you be using them, too?
The short answer, is no, but there are some exceptions. Let’s take a closer look.
Why are Companies Using Them?
There are several reasons why a company may choose to divide their website up into a number of subdomains. The most common (and valid) reason is based on infrastructure concerns. In some cases, the way a website was initially constructed makes it very difficult to add new content in any other way.
Even if it is necessary, though, it isn’t just something that a company should do for small endeavors. It’s more something that would be useful for larger promotions, online services, and other similar developments.
Subdomains are a very flexible way to do this because it usually doesn’t cost anything extra to add them. The domains you own are usually allowed a certain number of subdomains.
There are also some major websites that will use subdomains to segment their audience. Examples include en.wikipedia.org, or newyork.craigslist.com. In these cases, it is unlikely that users will have any other need to visit ja.wikipedia.org, so the company often finds it more effective to divide their content for ease of organization.
Along those lines, language concerns and geo-targeted pages may lead to subdomain usage. This allows the company to put all English content on one domain and then, as they move into new markets, they can use the same content, translated into another language, on the other subdomains.
However, most of these instances can be handled just as well with a subdirector or subfolder, so unless your website is limiting you in some way, it’s usually recommended to avoid subdomains.
Where It Went Wrong
There was a time when subdomains were considered the right way to go. There were several potential reasons why a company would divide up their website, but most of them (like those above) have proven to be ineffective at best.
There was a time when one could argue for the merits of themed subdomains. In other words, a company that sold red widgets and blue widgets might have a domain for red.widgets.com and blue.widgets.com. The hope was that the search engines would treat them as separate websites and rank them both on the first page.
Of course, some companies also tried to game the system. Since the search engines recognized subdomains as independent websites this seemed like an opportunity to link back and forth and improve rankings. There was also a theory that, since Google was actively trying to limit the number of results from a single company, this could help secure more than one spot on the front page for the same business.
It doesn’t take Google too long to see when that kind of thing is going on, though, and while it’s unlikely that linking between subdomains will hurt your rankings, it’s also unlikely that it will be more effective than simply putting your best, sharable content on a single, primary domain.
Potential Problems with Subdomains
There are several reasons why subdomains are no longer considered best practices for online companies. First of all, it is very much like dealing with two full websites, each with their own online marketing demands. That can be quite a challenge, especially if you’re just starting the business.
Subdomains can also cannibalize your own rankings. Search engines are unlikely to rank both your domains these days, and that means you’ve spent a lot of time and effort trying to get two domains to squeak onto the results page that you could have spent ensuring that a single domain dominated the results.
An SEO Advantage
While Google hasn’t officially stated one way or the other, most tests in this area suggest that it’s better to stick with subdirectories than use subdomains. Several tests have shown that when a subdomain is incorporated back into the primary domain, the rankings tend to perform much better.
Having said that, though, subdomains can be used in certain circumstances. They are often easier to use from an infrastructure perspective, and it can be a way to cope with extremely high traffic. However, when it is possible, it’s normally recommended that the subdomain be switched over to the primary website as soon as possible.
From an online marketing and growth perspective, companies should normally focus on directing as much traffic as they can to the great content on their main domain. This way, all the link juice and domain authority that you’re building can benefit your overall growth strategy and your efforts won’t have to be divided near as much.