You Shouldn’t Rely on Rel Canonical

When the rel=canonical tag came along it was like a breath of fresh air amongst pretty much every SEO on the planet. This wonderful new tag would solve the problems they’d be having with duplicate content by allowing them to put a source URL on a page where content had come http://www.digital-online-marketing.com/wp-admin/php?post=440&action=edit&message=1

However, a lot of users misunderstood this powerful tag and instead put the root domain inside the tag and left it, causing pages to disappear from the SERPs completely. Here’s an example of what they placed on every page:

<link rel=”canonical” href=”http://www.digital-online-marketing.com/” />

Some people might be scratching their heads and wondering what’s wrong with the above – the problem with the above is that when distributed across an entire website it is telling Google that every page has the same content as the index so put all value into that page instead – uh oh. An article on SEOmoz by Dr. Pete demonstrates how catastrophic the mis-use of this tag can be.

When not to use the tag

You shouldn’t use the tag if it’s a quick fix to a problem such as www / non-www. If this is the reason then you should just decide which site you’d prefer and set up a URL rewrite using .htaccess.

Another big no-no is to not use the tag if there is no chance that there will be duplicate content issues throughout your site. For example, if you have a 50 page website where every page is different and each has a set URL that never changes you will not need to add a canonical tag – it’s pure overkill!

When to use the tag

A perfect example of correct use of a rel canonical is on an ecommerce website. They have hundreds or thousands of products which may span across multiple categories and have different URLs. The description and technical specification of these products will be identical on each of these pages, but the breadcrumb and URL will be different for each time it appears which is correct. For something like this, the implementation of the canonical tag would be useful to prevent any duplicate content penalties.

Take it with a pinch of salt

The above example of an ecommerce website using rel canonical is also the perfect example of why Google is clever. If you think about the technical specifications and descriptions of certain products, they’re going to be on multiple ecommerce sites throughout the web, most of which will be ranking well in Google, so what’s the canonical URL then? Chances are there isn’t one, so external sites’ content may not be classed as duplicate*.

*This does not mean that site owners should not write their own content for products. Creative copy is something that will not only help sell a product, it could also have other benefits such as increased ranking.

Conclusion

It’s undeniable that rel canonical is both very powerful and very useful but it should not be taken lightly. It should only ever be used when absolutely necessary and not as a quick fix or as a way to boost rankings because it is more likely to product a negative result.

Written by Jason John Mills