Canonicals Can Hurt Your SEO If Not Used Correctly
Posted in General on February 25, 2011 | No Comments
The Canonicals of Naria is a crazy SEO adventure you might have the misfortune of going on if you don’t understand what canonicals are and try to use them anyways. At least that’s how I like to refer to this problem…
Google created the canonical element in order to help websites choose their preferred URL of a page that has more than one URL that can be used to access the same page and/or content.
<link rel="canonical" href="http://example.com/" />
A page on a website can accessed tons of different ways. For example a homepage could possibly be accessed the following ways:
- example.com
- www.example.com
- example.com/
- www.example.com/
- example.com/index.html
- www.example.com/index.html
- example.com/index.html?page=etc
- www.example.com/index.html?page=etc
- example.com/index.php
- www.example.com/index.php
- example.com/index.php?page=etc
- www.example.com/index.php?page=etc
… and so on.
All those URL’s point to the same exact page with the same exact content, but all the URL’s are different. There are tons of possible URLs that could be used to access a page on a website.
Is Google going to mark you down for this in their search results thinking that it’s duplicate content? No. Is Google smart enough to know what to do here without a canonical? Yes.
If Google doesn’t find a canonical it will choose the version of the URL it thinks is best. However, Google seem to be still in the process of fine tuning the use of this new element. If this element isn’t used correctly it is possible to do more damage than good to your websites search engine rankings.
Google will try to fix most errors that can occur when using the canonical element, but it’s still possible to hurt your SEO if used incorrectly.
Corrected by Google
- Infinite Loop
Page A points to page B, but page B points back to page A. This creates an infinite loop. - Not Found
Page A points to a page that doesn’t exist. Page A will still be used because Page B doesn’t exist. - Uncrawled
Page A points to a page that hasn’t been indexed by Google yet. The new page will be crawled and indexed. - Sub Domains
Page A points to page B at a different sub domain. Supported by Google. - Cross Domains
Page A points to page B at a completely different website. Not supported at first, but support has recently been added.
Possible Problems
- Chaining
Page A points to Page B which points to Page C, etc… This can also easily cause errors, so it’s recommended that the canonical point to the final preferred URL. - Relative URL
Page A points to page B relative to where page A exists. While this will work it’s recommended that you use absolute URLs with canonicals because errors could easily occur if pages are moved around. - WWW vs No WWW
Page A points to page B with no WWW in the URL, but the site uses WWW in the URL. Google says this can still cause possible errors, but they will try to correct the error.
Negative Effects on SEO
Pointing every page on the site to page A. If you put the canonical in an include file that is used for all your pages it’s possible to accidentally make this error. There was no mention by Google that they will try to correct this error. Other users making this mistake have reported that fewer and fewer pages started showing up in search results. This is because this is telling Google that your preferred version of every page on the site is the homepage URL.
In Conclusion
Make sure you fully understand the what a canonical is used for and what it is not used for before you try using it. I would recommend not using the canonical at unless you need to because using it incorrectly could possibly hurt your SEO and send you on a crazy Canonicals of Naria adventure just to try and figure out what’s wrong with your website.