First a definition. A subdomain is a website that hangs off of your main website. For example, my website is alextran.com.  My domain is “alextran” and my third level domain (TLD) is “com.”

If I were to install a subdomain called newsletter, for example, it would be accessed by typing “newsletter.alextran.com.”

The subdomain would rely on the domain name server or DNS in order to work, much like the domain alextran.com. So installing a subdomain would require that you wait until it gets added to the DNS before you could use it.

So why would people install a subdomain as part of their website design? One reason would be to add a different section or category to their website. The newsletter subdomain example that I gave above would be a potential use. I could also add a subdomain for “services”, “seo-web-design”, “training” and so on. The subdomains would then be:

services.alextran.com, seo-web-desgin.alextran.com, and training.alextran.com.

I could have done this, but I didn’t. Here are two reasons why.

1. Most people don’t understand subdomains. Since they don’t understand it, they don’t know how to access it. Most people do understand subfolders for categorization. For example, most people would understand “alextran.com/training/” rather than “training.alextran.com.”

2. The search engines have a thing against subdomains, at least according to my tests. I have put up several websites with subdomains and compared them to websites that I built using folders. More often than not, the search engines — Google — didn’t like the subdomains. If I put up a website too fast with subdomains, Google would deindex the whole website. This was not a good situation.

Based on my experience over the last 9 months, I have avoided putting up websites with subdomains.

Should you install subdomains? It’s up to you. I don’t. But if you do decide to install subdomains, put them up slowly. Don’t add too many subdomains too fast. You may find yourself deindexed and all that hard work would go to waste.