Canonicalization & SEO : Should I use WWW or not?

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A Search Engine Journal reader wrote to ask :What’s preferable: www- version or non-www version? Are they the same? (Which version are people more likely to link to? Which one is ‘traditional’?)

We often come across websites that are accessible by both the www and the non-www version of its URL. While apparently both the URLs look the same, the search engines can treat them as separate sites altogether. This is something known as a canonical issue.

In one of his blog posts, Matt Cutts said:

“Canonicalization is the process of picking the best url when there are several choices, and it usually refers to home pages.”


Matt further adds:

“For example, most people would consider these the same urls:

* www.example.com

* example.com/

* www.example.com/index.html

* example.com/home.asp

But technically all of these urls are different. A web server could return completely different content for all the urls above. When Google “canonicalizes” a url, we try to pick the url that seems like the best representative from that set.”

Since the search engines treat the www and the non-www version of the same URL to be different websites, there’s a risk of duplicate content issues arising because of the same content served on both the URLs.

Search Engine Roundtable defines canonicalization as:

“choosing what single domain you want to use for your site, and what single URL should be used to request each of your pages, having urls that are outside this standard can cause problems in the search engines”

Besides that, if there are links pointing to both the www and the non-www version of a URL, the page rank and the link juice flowing in from all those links get split between the two URLs.

So now there arises a question, which one to choose and whether there is any ranking preference from the search engine perspective?

Regarding ranking preference, there is no such preference from any search engine. The search engines will rank whichever URL has the highest number of quality links pointing to it.

As far as choosing which URL to use in a website is concerned, we suggest the www version of the URL. This is because the www version has become a universally accepted standard for URL structures and because people are more likely to link to the www version instead of the non-www version (even if there is no www, people link this way out of habit).

But what if there are links pointing to both versions of the URL?

Just set up a server side 301 permanent redirection from one version to the other.

Matt says:

“Suppose you want your default url to be http://www.example.com/ . You can make your webserver so that if someone requests http://example.com/, it does a 301 (permanent) redirect to http://www.example.com/ . That helps Google know which url you prefer to be canonical. Adding a 301 redirect can be an especially good idea if your site changes often (e.g. dynamic content, a blog, etc.)”

Suggested Reading :

So, what are your thoughts on this www and non-www issue? Please feel free share your thoughts in the comments below.

Loren Baker
Loren Baker is the Founder of SEJ, an Advisor at Alpha Brand Media and runs Foundation Digital, a digital marketing strategy & development agency.
Loren Baker
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  • http://www.seosmarty.com/ Ann Smarty

    I did some experiments to that launching both non-www and www of the site.

    Google first picks up a non-www version even if I build links to the www- one.

    Then in some time (about 2 months) Google starts ranking a www version and just forgets about the other one.

    So… does it mean Google really “likes” the non-www versions more and picks the www one only if we encourage it to???

  • http://www.thebigfish.co.za Jansie Blom

    There’s no preference from search engines as to which to use. It does not matter. I agree with the article though, in that USERS are probably more comfortable with the www.

  • http://www.mmmeeja.com andymurd

    It depends on the URL and the site. For instance, adding www to tinyurl.com would be foolish but if you use subdomains (or multiple protocols) then http://www.mysite.com, http://ftp.mysite.com and mail.mysite.com all make good sense.

  • http://www.arielis.com David

    You can also set a preferred version, with www or without, using Google Webmaster Tools.

  • http://kennyhyder.com Kenny Hyder

    I have to respectfully disagree. www serves no purpose functionally, and although people may be familiar with this format, why do we need to continue using legacy protocols simply because its what average users are used to? I think more and more people are beginning to use and become more familiar with subdomains, and ultimately, www is just a useless subdomain. It is so annoying to see someone type in http://www.store.domain.com and have to correct them. Why can’t we break these ridiculous habits and misconceptions?

  • http://www.thebigfish.co.za Jansie Blom

    because convention is not a bad thing. sticking to what people know, is not bad.

    and yes, the masses need to be trained to move on to the next right way of doing whatever the next right thing is to do, but sometimes sticking to what people know is better than dragging them off to where they’re not comfortable.

    and given where i live, i can tell you, convention is good for here and now.

  • http://ezweblogic.com Arif Aldoseri

    It all means pick a convention and stick to it. I personally prefer not to use www at all.

    It actually makes sense. Search engines see things as they are, unlike humans, we tend to interpret things, substitute, invert, manipulate, remap, or totally ignore an otherwise a clear fact. Search engines are faster, but not necessarily smarter.

    You should be happy, you’re smarter than Google, even though they make more money ūüėČ

  • http://mail-blast.com Andrew

    I’m with Kenny. The www subdomain is pointless. But I’m not about to stop supporting it. Allow people to type in www and then quietly redirect them to the proper domain, would be my advice.

    And set the redirect up so that it works for the whole site, not just the homepage (i.e. http://www.domain.com/deep/link/ redirects to domain.com/deep/link).

    It’s pretty easy to configure most website to do this either through code or through server configuration. It does seem noticeably to help with SEO too.

  • http://stevepenny.com Steve Penny

    I do SEO for some very large corporate websites and when I study the link architecture of links pointing to a site, I am seeing a strong trend in people simply dropping the www. when they make links to a site. The other trend is the increase in email addresses links which drop the www. Personally, I think someday the www. will look archaic. Until then, we live in confusing times regarding this issue and best defense is a 301 redirect to the version you prefer. GoogleBot doesn’t always get canonical issues right and when it doesn’t it splits your links… page rank leakage!

  • http://www.amid.com/werd Rudy

    Look at this site, it uses www prefix.

    I don’t think it’s going away any time soon.

  • http://www.virtualdreamer.com Brad

    Why can’t the big Kahuna’s of the Internet simply drop the www? If something has no value then eliminate it. I cannot see ,10 years from now, the use of WWW . So, you big honchos, get rid of it!

  • http://www.mcelroyfilms.com Ben

    Does this hurt your google rank if you have both www and non www links floating around?

  • http://www.articleslens.com Gama

    Everybody will agree here that you can never duplicate domain names. Every domain is unique so why complicate things?

    Try to type in your domain name witout “www” on any browsers and hit enter on your keyboard, you will understand what I’m saying.

  • http://andrewpritchard.com Andrew

    @Gama,

    If you’re saying that a user can enter either http://www.domain.com or simply domain.com and arrive at the same place, then you may be right in most cases. But is has nothing whatsoever to do with the browser.

    Where you end up when you type a URL is determined firstly by DNS and secondly by the site’s configuration. There are many examples where leaving the www off will take you to different content. That may not be advisable, but it *does* happen.

    It will take users years to stop using www. Until they do, I suggest we continue to support it, but not encourage it. Redirect users behind the scenes to domain.com when they type in http://www.domain.com would be my advice.

  • http://www.swr24.com Lana Galileo

    What about wordpress permalinks with friendly links, they just change original page to story, but old page is still active and accessible, its ok it redirects… but what if it dont redirects, i have some website where i cant redirect this mod rewritten links to new and im afraid im getting problems because of that… any ideas how to redirect dynamic links to static one?

  • http://www.abouttiyo.web.id Tiyo Kamtiyono

    Cool article, really thanks. This encourage me to add a www prefix to my blog

  • http://www.abouttiyo.web.id Tiyo Kamtiyono

    Cool article, really thanks. This encourage me to add a www prefix to my blog

  • http://novoia.com Joey

    Personally, I’m hugely against www. It just serves no purpose. It’s ancient. I mean, look at the popular companies today like Twitter- they don’t use www.

  • http://www.techiebin.com Arup Ghosh

    I think its better to use a www before domain name as “www.domain.com” is a universally accepted url structure.

  • http://www.centpage.com ritwick

    Well after reading your post i decided to drop the www from my domain name. As both versions refer to two different sites to search engine spiders it’s better to have one version and then redirect another version to it preferably the non www version. Henceforth i’m starting websites with no www in domain name. Thanks for this great article.