A decision to use either subdomains or subdirectories may arise when a company is looking to implement and integrate a live blog to their site. They would toss over blog.mycompany.com or mycompany.com/blog. Both are very different and treated very different. The first option, blog.mycompany.com is a subdomain and is seen as a separate domain independent of the root domain, mycompany.com. On the other hand a subdirectory like mycompany.com/blog is basically a folder that is on the same root domain. It is treated the same as the root domain but just a categorizing folder. It is like a label to say everything with this subdirectory is similar in a certain way. In the above example if we decided to use a mycompany.com/blog everything in that directory would be a blog post.
From a SEO perspective subdirectories are much better as they are seen as folders within a root directory and will share the hard earned page rank and link juice. The page rank and link juice diminishes as you go deeper into sub directories so it is best not to create too many directories within directories. At most I would recommend going no further than 2 subdirectories deep. Subdomains are treated separately to their root domains and is considered a different site altogether.
Recommended times to use subdomains
- Completely different information or product – You may choose to use a subdomain when you have a website that has multiple different themes, ideas or distinct product lines. This is a good way to separate content and organize information in a logically and clear manner for users to interpret. An example of a use of a subdomain for this purpose is news.google.com. Their news search is a completely different product that they offer so they have decided to host it on it’s very own subdomain.
- Multiple listings in SERPs – With subdomains it is possible to have your site rank multiple times for a single query. Google will display a maximum of two URLs from the same domain for any given query. With subdomains you are able to rank more than twice and potentially saturate the SERPs.Remember search engines treat subdomains as being separate so it is possible to rank more than twice for keywords, especially brand related searches. SEObook does an excellent job with this for the keyword “SEObook”. They use subdomains such as tools.seobook.com and training.seobook.com.
- Target Particular Keyword – You may want to use a subdomain if you are looking to aggressively target a particular keyword. For example if you run a pet store and you want to try to rank for the keyword “dalmatians” you may set up a subdomain – dalmatians.petstore.com. You will need build quality links to this new sub domain preferably with the keyword, dalmatians as the anchor text. With the appropriate resources you are able to become more competitive for keywords that you target with multiple subdomains.
Recommended times to use subdirectories
- For smaller sites – Subdirectories are more appropriate for smaller sites as it keeps all content in one place and just categorises them by basically putting them into folders.
- Keep all page rank and link juice – Probably one of the strongest arguments to using subdirectories is all content shares the same page rank and link juice from the root domain. In the short term it gives the content in subdirectories a much better chance of ranking. Any link building to the content within subdirectories benefit the site as a whole. Subdirectories allow site to grow in authority much faster
- Site Organization – Subdirectories are a good way to organise content on a website. Subdirectories allow you to group similar pieces of content or information. It is similar to a folder structure on a computer and can be treated/used in a similar way.
As you can see both subdomains and subdirectories are treated very different by search engines and have completely different effects on SEO. In most cases subdirectories will be most beneficial as you are building authority and strength to the single domain with all your efforts however there are times when subdomains just make more sense.