The Canonical Tag
Consider this problem. I’ll use this domain as an example but the same can apply to any domain:
http://maximise.ie
http://maximise.ie/index.php
http://www.maximise.ie
http://www.maximise.ie/index.php
All of these URLs point to exactly the same page.
If you’re running any online ad campaigns, by the time we take into account campaign URLs with tracking codes inserted, for example:
http://www.maximise.ie/index.php?campaign_id=35
http://www.maximise.ie/index.php?campaign_id=36
- there may be hundreds or even thousands of URLs all pointing at the same content with slightly differing URLs.
What’s the problem with this you may ask? Unfortunately, search engines aren’t yet sophisticated enough to tell that these are all the same page. They try, but they don’t always get it right.
If people link to variations of your URL, when a search engine spider crawls these, the score assigned to your page gets spread among the different versions, diluting the power of those inbound links and causing the variants to compete with eachother in the search engine results.
In a rare joint effort to help webmasters with this problem, and also to help clean up the search results, Google, Yahoo and MSN have announced the canonical tag. This is a meta tag placed into the the HTML of your page with the canonical version of your URL. Another way of putting it might be that this URL is the ruling, or master version.
If one of your URLs is www.example.com/index.php?campaign_id=35, you would most likely want to make the canonical URL simply http://www.example.com.
In the HTML of your page, the tag should look like this:
<link rel=”canonical” href=”http://www.example.com/”/>
Voila! Next time your page gets crawled, the score which would previously have been assigned to the variant URL is now assigned to the one true, or canonical, version of your URL – hopefully resulting in a improvement of your position in the search results.
Published in categories: Google, Live-Search, Meta Tags, Yahoo
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