Google and a few other search engines may see your domain and your subdomain(s) as a separate web site. If the information is the same on the domain and subdomain you may be penalized for duplicate content and your rankings and traffic could suffer severely.

What does this have to do with WWW? Well, the http://mysite.com and the http://www.mysite.com versions of a web site may be seen as separate sites for the very same reason. http://mysite.com is the true domain name while the http://www.mysite.com (the www version) is technically a subdomain.

This is common on most hosts. You can easily verify this on your site by trying both versions in your browser. Try the following:

1. Type http://mysite.com (replacing mysite with your domain name) in your browser address bar. Did it change to http://www.mysite.com? If it did you probably don’t have an issue. If it didn’t, go to step 2.
2. Type http://www.mysite.com in your browser. Did it change to http://mysite.com? If it did you probably don’t have an issue. If it didn’t, move on to the next step.
3. You have what are referred to as non-canonical URLs.

Google engineer Matt Cutts defines canonical URLs as follows: “Canonicalization is the process of picking the best url when there are several choices, and it usually refers to home pages.”

So, once again, what does this have to do with my site? Well, with two addresses with which to access each page on your site, your PageRank could be split amongst the two “sites”. So, the www page could have a PageRank of 2 and your non-www may have a PageRank of 3. Theoretically, if you could concentrate that power into one page you could end up with a PageRank of 4 or more.

To further clarify: if one backlink pointed to www and one to non-www then you may only benefit from one link – not the two you actually have. Canonicalization can concentrate your backlink power.

How do you do it? The process, called redirection, differs slightly depending on whether you are on a Windows or Unix or Linux server, can concentrate your PageRank and prevent duplicate content possibilities. It is not a strategy that beginners should attempt on important or live web sites. If it’s done improperly you could really suffer. If done correctly you could get a nice boost. Seek professional advise.

Here’s how it works. The first step will be to choose whether to use the www or the non-www version. There are reasons to select one over the other and you can read about them in one of our other articles. Again, some professional advice can be helpful because there are several factors which must be considered prior to attempting canonical redirection.

For this example, let’s examine the Trinity web site. If you click on the following link: http://trinitysem.com you will automaticallybe redirected and your browser will resolve to http://www.trinitysem.com.

So, it is important to prevent the possibility of duplicate content penalties and to concentrate PageRank. And it is easily done by an experienced web master or SEO.

Note: I just posted about how to choose the www or non-www version of your URL for canonical purposes. Click to read more.

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