The debate over the merits of using subdomains versus subfolders (also known as subdirectories) when structuring websites has been going on for a number of years. While each option has its advantages and disadvantages, you need to understand that neither the subdomain nor the subfolder is the most appropriate solution in all cases.

Confusing the issue even further is the fact that changes in search engine ranking algorithms that impact website architecture and optimization may affect your choice of how you structure your website. A site that’s structured to be easily optimized for search engine ranking is an important consideration when choosing between subdomains and subfolders.

A website is similar in many ways to a library, with a large number of files containing text and visual information that are retrieved and served up each time someone visits your site. Subdomains and subfolders are simply two different methods of organizing and storing your content.

The Difference Between Subdomains and Subfolders

• A subdomain is basically a separate website with its own home and identity that is connected to your main website through a shared root domain. A subdomain looks something like this: blog.joesautorepair.com.
• A subfolder is a file extension of your main site domain and resides within your main website files. Here’s what it looks like: joesautorepair.com/blog.

The Pros and Cons of Subdomains
Subdomains are a good option when the content of your main website is so varied across product lines that you find it necessary to have separate homepages for each major product grouping. Say you operate a construction business offering plumbing, electrical, and roofing services. It might be advantageous to create a separate subdomain for each of your major products within the framework of your main construction business domain. Separate niche sites generally rank better in the search results than other forms of website structure.

If you operate offices in multiple geographic regions that are searched for by users in each area, subdomains might be your best choice. This would allow content and site optimization to be customized for each location. For example, a law firm with offices in Los Angeles, San Francisco, and Las Vegas might set up the main website as brownandsmithlawoffices.com, with separate subdomains such as losangeles.brownandsmithlawoffices.com and so forth.

The problem with subdomains is that much of your SEO efforts will be split among each subdomain rather than being focused on your primary website. In essence you’ll be running a separate SEO campaign for each subdomain. Another disadvantage is that your content creation and social media workload will increase for each subdomain that you add.

What About Subfolders?
For the less technically savvy webmaster, setting up and maintaining subfolders may be an easier and less time consuming option.

In many cases, your overall search rankings will improve due to the fact that all of your pages and subfolders will benefit from a single and more focused SEO effort.

Newer or smaller websites will find it easier and quicker to build site authority and trust for one website using subfolders rather than having to start from scratch as would be the case with running multiple subdomains.

The major downside of using subfolders is that the ranking power of inbound backlinks and keyword authority may be diluted by being spread across the entire main website.

What’s the Bottom Line?
In most cases, less experienced webmasters or those webmasters running a website with less than 10,000 pages will benefit more by structuring their site around subfolders. They’re easier to set up, they maximize SEO efforts, and they lessen the amount of time required for content creation and social media networking.