This is an article about “Add-on domain vs Subdomain vs Subdirectory”. It’s a reply to a member’s question.

Here’s her question:

“Hi Kenneth, just like to know exactly what is the difference between an add-on and a sub domain, and what do you use each one for? I know you can host several different websites, or pages but, which do you use for what?” - Glenda

Hi Glenda, an add-on domain is a new domain, such as domain123.com, domain456.com, domain567.com. You have to buy a new domain name whenever you want to add an add-on domain to your hosting account. A sub-domain is a domain derived from your existing domain. Let’s say your existing domain is domain123.com, you can have unlimited sub-domain such as abc.domain123.com, xyz.domain123.com and so on.

Whenever you want to start a new project, there are 3 types of website structure you can consider.

1) A brand new domain (i.e. an add-on domain)
2) A subdomain
3) A subdirectory (simply a sub-folder of your domain)

If you are starting a new project in a completely different niche, it’s obvious that you should buy a new domain and host it as an add-on domain. But if you are starting a new project in the same niche, you will have to think which of the 3 structures above you should adopt.
Let’s say you have a website called esuccessonline.com, and you are thinking of starting a blog related to online success, you have 3 options to structure your new blog.

1) A brand new domain - you can call it esuccessonlineblog.com
2) A subdomain - you can call it blog.esuccessonline.com
3) A subdirectory - you can call it esuccessonline.com/blog

Below are some issues you should consider when deciding which option to choose.

1) From SEO perspective

If your original website esuccessonline.com is already well established, with a decent PR, you may NOT want to start a brand new domain just for your blog. This means option 1 is out.

If you use option 2 or 3, you can pass the credibility of your original domain to your blog, which is in either a subdomain or subdirectory. This will help your new blog and subsequent blog posts to get ranked in the search engines faster and better. Also your new blog content will help boost your original website. So it’s a win-win situation.

2) From branding perspective

If you plan to brand your blog in the future, then you should start a new domain called esuccessonlineblog.com. In general, as long as you intend to brand your new project as a new entity, it’s always a good idea to register a new domain for it.

3) “Expandability” issues

If you envision that your blog is going to be very big and it may require a lot of server resources, then it may be a good idea to start your blog in a new domain or subdomain, not a subdirectory.

To understand why, let me explain the technical difference between a subdomain and subdirectory. A subdomain can be technically treated as a new domain, in the sense that it can be hosted separately from its root domain. This means you can have blog.esuccessonline.com and esuccessonline.com hosted on different servers. But this cannot be done for esuccessonline.com/blog.

As such, if you expect your blog (or whatever new project you have) to consume a lot of server resources, your current server may not be sufficient to satisfy your needs. In such case, if you start your new project in a new domain or subdomain, you can always host it on another server in the future.

One good example is Google.com. Google.com is a brand. Everything it does must enhance its brand “Google”. So when Google started Google Map, which obviously requires a lot of server resources, it only has 2 choices. Google can either call it GoogleMaps.com or maps.google.com.

And you should know their decision. It’s logical to make that decision too. They call it maps.google.com.

4) To boost your Alexa ranking

More and more people, especially in the internet marketing niche, look at the Alexa ranking of a website as a means to gauge the credibility of the website. So if you want to boost the Alexa ranking of your website, it may be a good idea to put all your projects under one domain. This means you can either use a subdomain or subdirectory.

Take Google and Yahoo as a case study. Google names its international websites in separate domains, such as google.com.sg, but Yahoo names its international websites as a subdomain, such as sg.yahoo.com. The result is yahoo.com is now ranked #1 in Alexa ranking. I believe if Google were to consolidate all its international websites under google.com., it should rank #1 in Alexa ranking.

The Conclusion?

There is no conclusion. It really depends on what you want to do now and in the future. New domain costs money but it looks professional. Subdomain is free and it’s technically as flexible as a new domain, but it’s not as professional. Yet, if you want to create a mega website like Google.com, subdomain can give you a lot of leverage. Subdirectory is the simplest option for website structuring. If branding and server requirement are non-issue, it’s always easier to just use a subdirectory.