Using Sub Domain and Sub Folder for Websites

The issue between sub domains and sub folders is something which apparently has been going on for a long time. You would think with all this talk there would be a rule about it by now. Sadly, there aren't any (that I know of). Choosing which to use can be tricky but there are some basis things to remember when making the final decision so you don't end up misusing them. Funny enough, I don't have to look too far to point fingers on the misuse of sub domains and sub folders...

Sub Domain

These are stand alone domains found under and hosted by the main or root domain. Most times, sub domains are treated as unique domains, even though the name is attached to it. Some examples of sub domains are:

• abiolaomoniyideveloper.blogspot.com
• blog.myonepage.com 

Search engines and crawlers treat sub-domains uniquely and separately from the main domain. That's the reason why even though you get hosted by blogspot or wordpress you not going to find your blog anytime soon unless you do some work!

Sub Folder

These are web pages which are physically and structurally found on the root domain/website (a sub domain can have a sub folder, but a sub folder can't have a sub.domain) but in lower level, so to speak. Sub folders have a lot to do with hierarchy and file structure. They are treated as part of the main domain, however, the search engines see them as inner pages so it's harder (but not impossible) to get good ranking for sub folders pages.

A Simple Illustration

Let's have a look at this 'organisational structure' diagram which is a Wikipedia-like website that gives various information on Earth, Continents, Countries, Towns and local areas. The hierarchy is something like this:

• Earth - Top level
• Continents - 1st level
• Countries - 2nd level
• Cities - 3rd level and
• Local Areas - 4th level and so on...

An Organisational Structure for Sub domain & Sub folders

A sub folder implementation could have URLs which look like this:

http://www.earth.com/africa/nigeria/lagos/ikeja/...

http://www.earth.com/europe/united-kingdom/newcastle-upon-tyne/benwell/...

However, a sub domain implementation could look like this:

http://africa.earth.com/nigeria/lagos/ikeja/... 

http://europe.earth.com/united-kingdom/newcastle-upon-tyne/benwell/...

In a situation like this, I would consider the sub domain implementation because each level should have its own  content and be able to stand on its own. That means each continent would be a sub domain of the main domain, Earth. However, if there wasn't much content on each level then maintaining a sub domain would be harder and more expensive as there's little or no content to attract backlinks.

I think it's usually easier and cheaper to have sub folders except in necessary situations. Here are some things to consider when considering sub domains and folders:

• Sub folders are easier to manage from a search engine POV because they are seen as part of a website; page rank flow more easily. 
• Sub domains are handy when you want to show an association between the main and sub domain, which can stand on its own.
• Sub domains are more expensive short-term because you need new content and backlinks for the website, considering it can't get much link juice from the main website.
• Since sub domains are treated as separate websites, having a strong interlinking between both domains can help search ranking, but this can't be compared to backlinks from unique domain (see Link Evaluation Refresher #4).
• In the long run, sub domain can get multiple listings and ranking (root domain ans sub domain) on search results a lot easier than sub folders. This lead to more clickthroughs

When it's all said and done, sub domains and sub folders have their uses but I believe you need to know and have a good reason for using either. That comes down to planning ahead, which is not always an easy thing to do since business plans and ideas evolve and change over time. If a mistake is made, it's not too difficult to  rectify it but try to avoid using 301s redirects since they aren't as effective as they used to be.

Are there other reasons you've come across for using sub folders and sub domains? And have you found benefits for using one over the other? Please share your thoughts and opinions in the comment, would love to hear about it.

Oh and the culprit for misusing sub domain was, yes you guessed it, Me! I should have gone for tolafamakinwa.net/seo instead of seo.tolafamakinwa.net but that's for another day.