Search Engine Optimization :: Lyndsay Walker :: Toronto, Ontario

Duplicate content no more

Today at SMX West, the three big search engines (Google, Yahoo! and Microsoft) announced a new tag to help reduce duplicate content on the web.

This new tool is called the “canonical tag”.  If you’ve spent some time learning about SEO before, I’m sure you’re familiar with the term.  Canonical refers to a page that has more than one URL.  For example, the www and non-www versions of your web site are considered different sites.  Google has had a tool through Webmaster Tools for some time to help with this, but the announcement of this new tag comes from all three search engines meaning that they *should* all obey it.

How does it work?

Simply enter the canonical tag within the head section of your web page.  Within the tag, you can declare the URL that should be indexed and crawled.  This will tell the crawlers that any other page with the exact or very similar content should not be indexed and link juice should instead be passed onto the declared URL.


<link rel=”canonical” href=””/>

Other Tips

  • Works on domains and subdomains
  • Does not work across domains
  • Relative URLs are okay, but absolute URLs are better

This is really exciting news… I only wish I had this information a month ago!

  • Martin Greenwood says:

    This is amazing news and will help greatly at where I work! Thanks

    February 12, 2009 at 2:53 pm
  • Chase Granberry says:

    Okay … so what if another site picks up your content and uses the same tag but with their URL? Or does this strictly have to do with what’s displayed in SERPs, the ‘’ or the ‘’?? Or, is it simply to declare original content within a domain? I’m confused as to how this deals with cross-site duplicate content. Thanks for the good info.

    February 12, 2009 at 2:54 pm
  • lyndseo says:

    Chase, the way I understand it is that it really only helps for duplicate content within one domain. Other sites can still take your content and publish it on their own site with their own URL in the tag.

    February 12, 2009 at 2:58 pm
  • Rob says:

    This is great, and I love the simplicity. (I have to admit there was a doubt in my mind when I first read it.)

    I guess what impressed me more than anything was that the three search engines have got together, discussed it, developed a solution together and are running with it. Great job.

    Sphunn :)

    February 12, 2009 at 3:06 pm
  • Chase Granberry says:

    Sweet … thanks for the clarification 😀

    February 12, 2009 at 3:49 pm

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