Google Now Honors Canonical Specification Hint: link rel="canonical"

5 replies
If you're like me, you're wondering what the hell Canonical means. LOL

Here's the new Google announcement that will clear it up for you:

Originally Posted by Google Webmaster Central

Carpe diem on any duplicate content worries: we now support a format that allows you to publicly specify your preferred version of a URL. If your site has identical or vastly similar content that's accessible through multiple URLs, this format provides you with more control over the URL returned in search results. It also helps to make sure that properties such as link popularity are consolidated to your preferred version.

Let's take our old example of a
site selling Swedish fish. Imagine that your preferred version of the URL and its content looks like this:

http://www.example.com/product.php?item=swedish-fish


However, users (and Googlebot) can access Swedish fish through multiple (not as simple) URLs. Even if the key information on these URLs is the same as your preferred version, they may show slight content variations due to things like sort parameters or category navigation:

http://www.example.com/product.php?item=swedish-fish&category=gummy-candy



Or they have completely identical content, but with different URLs due to things such as a tracking parameters or a session ID:

http://www.example.com/product.php?item=swedish-fish&trackingid=1234&sessionid=5678



Now, you can simply add this <link> tag to specify your preferred version:

<link rel="canonical" href="http://www.example.com/product.php?item=swedish-fish" />

inside the <head> section of the duplicate content URLs:

http://www.example.com/product.php?item=swedish-fish&category=gummy-candy
http://www.example.com/product.php?i...sessionid=5678


and Google will understand that the duplicates all refer to the canonical URL: http://www.example.com/product.php?item=swedish-fish. Additional URL properties, like PageRank and related signals, are transferred as well.

This standard can be adopted by any search engine when crawling and indexing your site.

Of course you may have more questions.
Joachim Kupke, an engineer from our Indexing Team, is here to provide us with the answers:

Is rel="canonical" a hint or a directive?
It's a hint that we honor strongly. We'll take your preference into account, in conjunction with other signals, when calculating the most relevant page to display in search results.

Can I use a relative path to specify the canonical, such as <link rel="canonical" href="product.php?item=swedish-fish" />?
Yes, relative paths are recognized as expected with the <link> tag. Also, if you include a <base> link in your document, relative paths will resolve according to the base URL.

Is it okay if the canonical is not an exact duplicate of the content?
We allow slight differences, e.g., in the sort order of a table of products. We also recognize that we may crawl the canonical and the duplicate pages at different points in time, so we may occasionally see different versions of your content. All of that is okay with us.

What if the rel="canonical" returns a 404?
We'll continue to index your content and use a heuristic to find a canonical, but we recommend that you specify existent URLs as canonicals.

What if the rel="canonical" hasn't yet been indexed?
Like all public content on the web, we strive to discover and crawl a designated canonical URL quickly. As soon as we index it, we'll immediately reconsider the rel="canonical" hint.

Can rel="canonical" be a redirect?
Yes, you can specify a URL that redirects as a canonical URL. Google will then process the redirect as usual and try to index it.

What if I have contradictory rel="canonical" designations?
Our algorithm is lenient: We can follow canonical chains, but we strongly recommend that you update links to point to a single canonical page to ensure optimal canonicalization results.

Can this link tag be used to suggest a canonical URL on a completely different domain?
No. To migrate to a completely different domain, permanent (301) redirects are more appropriate. Google currently will take canonicalization suggestions into account across subdomains (or within a domain), but not across domains. So site owners can suggest www.example.com vs. example.com vs. help.example.com, but not example.com vs. example-widgets.com.

Sounds great--can I see a live example?
Yes,
wikia.com helped us as a trusted tester. For example, you'll notice that the source code on the URL http://starwars.wikia.com/wiki/Nelvana_Limited specifies its rel="canonical" as: Nelvana - Wookieepedia, the Star Wars Wiki.

The two URLs are nearly identical to each other, except that Nelvana_Limited, the first URL, contains a brief message near its heading. It's a good example of using this feature. With rel="canonical", properties of the two URLs are consolidated in our index and search results display wikia.com's intended version.

Feel free to ask additional questions in our comments below. And if you're unable to implement a canonical designation link, no worries; we'll still do our best to select a preferred version of your duplicate content URLs, and transfer linking properties,
just as we did before.

Written by Joachim Kupke, Senior Software Engineer, and Maile Ohye, Developer Programs Tech Lead



Hopefully this will help those of us with multiple versions of the same content on our site.

If you are a programmer, do you think a piece of software that would do this automatically would be in demand?????

Respectfully,
Allen Graves
#canonical #google #hint #honors #link #relcanonical #specification
  • Profile picture of the author JayXtreme
    Yeah..I read about this yesterday...

    It's fantastic news.. SO many people don't even realise the importance of domain canonicalization...

    Peace

    Jay
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    Bare Murkage.........

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    • Profile picture of the author Andyhenry
      Originally Posted by JayXtreme View Post

      Yeah..I read about this yesterday...

      It's fantastic news.. SO many people don't even realise the importance of domain canonicalization...

      Peace

      Jay
      I don't give it any thought whatsoever and it doesn't seem to be hurting me.

      I think many people get too involved in the techy details when it's more productive to market your business than worry about the latest search engine variations. Even if some new rule came in that bumped your website up if you changed it - it'd still come second to me calling a new partner to promote my business or getting some products created.

      I have so many domains that I no longer have any interest in the nuances of domain seo.

      I've always found that promoting a brand does much better long term than trying to fit keywords into the domain or faffing around with internal structure.

      But then again, I usually only create a website if I know how to make money with it regardless of any sem factors.

      Cononical-shmonical



      Andy
      Signature

      nothing to see here.

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      • Profile picture of the author JayXtreme
        Originally Posted by Andyhenry View Post

        I don't give it any thought whatsoever and it doesn't seem to be hurting me.

        I think many people get too involved in the techy details when it's more productive to market your business than worry about the latest search engine variations. Even if some new rule came in that bumped your website up if you changed it - it'd still come second to me calling a new partner to promote my business or getting some products created.

        I have so many domains that I no longer have any interest in the nuances of domain seo.

        I've always found that promoting a brand does much better long term than trying to fit keywords into the domain or faffing around with internal structure.

        But then again, I usually only create a website if I know how to make money with it regardless of any sem factors.

        Cononical-shmonical



        Andy
        Whilst I do see your point Andy...

        Well structured sites always out-perform my lazy sites... the "time" it takes me to construct a "search engine friendly" site as opposed to one that I build lazy is not much difference and the benefits are well worth the extra bit of time...

        I think it is easy for people to say that others get too involved in the techy side instead of marketing their business, but for me.. it isn't an either/or situation, it's a "do both because it's neither here nor there on time and it works for me"

        I build a ton of sites(as do many people) designed to rank quick and high for shorter, more competitive keywords than your average niche site, so it pays me to play the Google game..

        But then again... I build many sites that are designed to profit richly from sem factors, knowing that should anything drastic occur.. I can still use it profitably.




        Peace

        Jay
        Signature

        Bare Murkage.........

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  • Profile picture of the author Andyhenry
    me too

    I just build it in so I don't have to think about it - that's the beauty of Wordpress
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    nothing to see here.

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  • Profile picture of the author Kurt
    Originally Posted by Allen Graves View Post

    If you're like me, you're wondering what the hell Canonical means. LOL

    Here's the new Google announcement that will clear it up for you:

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    Hopefully this will help those of us with multiple versions of the same content on our site.

    If you are a programmer, do you think a piece of software that would do this automatically would be in demand?????

    Respectfully,
    Allen Graves
    This would probably be better offered as a service, as it needs to be customized for each server with whatever "page making" scripts are installed on the server, such as individual forums, blogs, etc.

    And then, it's usually handled using an htaccess file.

    For a server admin that knows what they're doing, it's a pretty easy job for them, and there' a number of variables that I think require a real human for best results.
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    Discover the fastest and easiest ways to create your own valuable products.
    Tons of FREE Public Domain content you can use to make your own content, PLR, digital and POD products.
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