I recently moved from having a main site like www.example.com with a subdomain associated site yyy.example.com, to moving everything off the subdomain to a subdirectory like www.example.com/yyy/, with the same hierarchy underneath the subdirectory, and now yyy.example.com is just a redirect page to the subdirectory, so yyy.example.com/abc/page-x is redirected to www.example.com/yyy/abc/page-x and so on.

The effect has been that the traffic increased by several times (the total page views are more than ten times at the present rate) what it was to the yyy subdomain. Previously almost all of the traffic to the yyy subdomain was from the www site. This is from monitoring the old yyy site for a year or more.

I'm curious to know if there's any research or results which would indicate whether this is universal (subdirectories beat subdomains) or "just me".

  • +1 Your question is a very interesting by itself. But when you say the traffic increased by several times I suppose you are comparing the traffic of (the old traffic of www.example.com + the old traffic of yyy.example.com) towards the (new traffic of www.example.com), and NOT (the old traffic of www.example.com) towards the (new traffic of www.example.com), because in this 2nd case it would be obvious that the traffic increased. I know it seems trivial, but some people are not able to analyse traffic on subdomain and think webstats for main domain do already include the subdomain Commented Mar 28, 2011 at 12:50

6 Answers 6


I think the issue may be due to "trust" - search engines usually treat subdomains differently from the main domain, so if you moved some pages to a different domain or subdomain then essentially you are "starting from scratch". Whereas if you use subdirectories the domain is already trusted and pages may be indexed more quickly.

If your traffic is increasing it could be due to any number of things such as more links being picked up, or just a single link from a popular site like digg or stumbleupon.

One more point of note: PageRank is page-based, not site-based, so if each of the pages had the same number of links in they will have the same PR.

  • There aren't any significant new links or single links from popular sites.
    – delete
    Commented Jul 18, 2010 at 22:39

i just came across this info graphic from slingshot that might be of interest :

Reverse Proxy Infographic
(source: seomoz.org)


I believe it's to do with page ranking. Search engines treat subdomains as completely different sites from the non-subdomain and thus by moving your pages from the subdomain to the main domain, they will be picking up it's PR (which may be higher?).

It may also just a coincidence. How long have you been studying the traffic for?

  • I've edited the answer to point that. Studied traffic for one year at old site and one month since move.
    – delete
    Commented Jul 18, 2010 at 15:54

Rand Fishkin said, sub directory is good for many reason compare to subdomain, but when you read this official article from Google official blog, then you will see the link between subdomain.example.com and example.com/subdomain is same i.e. they treat them as internal linking not external. So I don't think subdomain and sub directory is impact on SEO, but moz said, we have tested, sub domain and sub directories many times, and we got very good result with sub directory in SERP. But john muller and matt cutts(Google Employer) said, there are no any difference between subdomain and sub directory for SEO, use whatever is easiest for you.

But you are also said, you are getting very good result with sub directory and similarly there are many of webmaster tested sub directory and sub domain. And they also think sub directory is good for SEO. So look's like there are some minor different between subdirectory/subdomain, Yes google claim it, there are no any difference, but may be there are one algorithm, that treat them in different way.


According to an article from 2011 on the google webmaster blog, subdomains are considered to be internal links for a website:


I know it is possible to create a different entry in google webmaster tools for multiple subdomains but it does not mean they are counted as different websites.

In fact, Matt cutts mentioned in a video, that they saw webmasters abusing subdomains in order to get more results on one page. By the past Google considered subdomains to be different domains but it is not the case anymore.

Then, Matt cutts also said that subfolders and subdirectories are similar.

Link to Matt Cutts videos about Subdomains Vs Subdirectories:


if you consider https, you will need one wildcard SSL certificate to protect all your websites with a different subdomain. Usually it is 10 times more expensive than a SSL certificate to protect one (www and non www) domain.


Matt Cutts of Google has basically stated, in reference to the 2011 Panda update, that subdirectories are treated as separate sites by the search engine. Your increase in traffic is probably due to the sum quality, NOT quantity, of your content.