How to build a bigger website – subdomains or subdirectories? Part 1

Subdomains or subdirectory? We’re often asked about the relative merits of these two approaches when developing a website. In the first of a two-part series, CSC’s Trung Tran examines the pros and cons of each one for marketing and promotion.

When should you use“” and when should you use “”? There’s no black-and-white answer to this frequently asked question, because whether you choose to use subdomains or subdirectories depends on your priorities and plans.

Structure_200wIn this first article, we’re going to look at the question from an SEO, marketing and promotional point of view. Then we’ll consider how the use of subdomains and subdirectories impacts on site set-up, management and maintenance.

The aim is to help you understand all the issues so you can make the best decisions when adding content or functionality to your website.

First, a quick primer. Subdomains are discrete domains that are part of the primary domain, and can be separate websites in their own right. For example “” may have subdomains called “” or “”. Subdirectories are simply part of the main domain, often folders of content, for example “”.

PART 1 – Marketing and promotion considerations

Subdomains and SEO
Both approaches are now equal in the eyes of SEO. In the past, using subdomains offered an advantage in SEO because Google treated each one as a separate host, returning two search results. However as some companies began to abuse this, Google adjusted its algorithm in response. Today, according to its Webspam team head Matt Cutts, subdomains and subdirectories are treated equally.

Geo targeting
While subdirectories can now be geo targeted, subdomains retain a useful extra targeting option. For websites hosted on a country domain [ccTLD], Google automatically associates the site with the corresponding region. However historically, for sites hosted on a gTLD (.com, .net, .org) the only option to set a geo target was at the root domain or subdomain level. Google has now made it possible to add subdirectories to its webmaster tools, meaning that they too can be geo targeted. Subdomains retain the option to be hosted on a separate IP address that could be targeted to the local area.

Online marketing
Their structure and ease of use makes using subdirectories well suited to increasing ranking and “link juice”, while subdomains can usefully allow for separate, targeted campaigns. Because subdirectories are linked to the main domain, they inherit SEO strategies, and global changes to SEO are filtered down to them. Their links to the home page also mean they get more “link juice” from search results. And because they share the same SEO and link-building strategy, subdirectories are easier to manage.

Google prefers large websites with unique, quality content. Subdirectories attribute all content to a single site, increasing ranking signals like authority, trust and domain strength.

While they lack these advantages, subdomains allow marketers to conduct specific campaigns that can use different link building and SEO strategies than those used on the main website.

Promotions and sponsorship
Subdomains are ideal for time-limited campaigns. When brands sponsor specific events or partner with other vendors or agencies, subdomains make it easy to set up standalone websites that can be managed by third parties. Easily deactivated once the campaign is over, websites based on subdomains reduce the risk of disruption to the main website.

In my next post, I’ll look at the pros and cons of subdomains and subdirectories for website and content management.

MORE INFO: For more information or to discuss your domain strategy, please contact CSC Digital Brand Services.