When it comes to SEO, there is a constant debate over which is better, subdomains or subdirectories. The simple fact is that there is no easy answer to this question. There are easy answers for some sites that already exist, but this does not help the webmaster that is trying to build a site or series of sites.
A subdomain will look like this in a browser, other.domain.com. The dot com is the TLD or top level domain, the “domain” is, of course, the domain, and “other” is the subdomain. The reason that a website would have a subdomain of this nature is because it is exclusive from the domain itself. Both the domain and the subdomain are completely different websites. From an SEO perspective that means that there are two websites that both need the same amount of SEO effort.
One may question why a webmaster would choose to use a subdomain, rather than a brand new domain altogether. The answer may be that a company is trying to make a name for itself, but wants to maintain two or more distinct divisions. This may have to do with brand recognition. Perhaps the company has a well-established client base and is just starting to establish itself as an online presence. Most of the time, in the past, a subdomain was devoted to company use, but that does not affect SEO and therefore does not warrant discussion.
The subdirectory is a very useful tool for a company or web site owner. It gives the ability to create a separate website without the need for an entirely new domain. Smaller companies and businesses will find that this is the way to go for SEO purposes. Even if there are no links from the higher domain to the lower subdomain, they are all handled with the same SEO efforts. The top domain may be the company and subdirectories can cover individual products or services.
Linking between the two will not affect how they are perceived by the search engines in any way other than being counted as inner links. Many CMS packages may be setting up subdirectories as the structure of the website without the webmaster even knowing it is happening. A subdirectory is a very subtle way of organizing a website. It is not considered separate by search engines in any way, shape or form.
Any good webmaster is going to be submitting a sitemap to the search engines on a regular basis. Using the sitemap system is a great way to begin to separate the subdomain and the domain. They should each have their own distinct sitemap and be submitted as two separate domains to the search engines. If this is done on a regular basis, then any links between the two will begin to be seen as outside links rather than inner links.
This is not to be taken as a way to establish backlinks without effort. Recent updates to the systems that the search engines use have changed the strength that backlinks carry anyway. Anyone that is trying to fool the search engines with elaborate wheels of links will do better to use separate domains. It is best to simply avoid systems that attempt to get around the proper building of websites, as they will eventually fail in the end.
While a sitemap is a guide to the search engines, it should not be thought of as a clear cut set of directives. It is also important that each domain or subdomain have an accurate sitemap. If changes are made, then a new sitemap should be generated and submitted. If this sounds like a great deal of work it is not. Making and keeping a clear work flow is important to SEO and business in general.
The Future of a Website
One of the issues that a webmaster should take into consideration when setting up a domain structure is where the site may be ten years down the road. While it is always possible to alter the way a set of websites is laid out, the SEO can be seriously altered. Not to mention the amount of trouble that it takes to completely redo the structure of a set of websites.
If the company appears that it is going to make continued growth, then it may be necessary to use subdomains. The additional effort in promoting the SEO may be worth the effort. Look at where the websites are going and where the company is going. The use of a subdomain makes a very clear SEO statement that each is a fully separate entity.
One thing to keep in mind when it comes to SEO is that games will eventually fail. Any website that is going to last for more than a year needs to use the fundamental basics of SEO and good strong website content. Search engines may maintain certain standards that make it difficult at times to become high ranking, but these standards are there to prevent less ethical webmasters from pushing the good websites down the list.