Brighton SEO: In praise of the Canonical tag

27th May, 2015

BrightonSEO tag2

Part of a series of posts that bring home the best of Brighton SEO for anyone who couldn’t make it. Our second post focuses on Pi Datametrics’Jon Earnshaw who reviewed how even the biggest of brands still suffer from keyword and content cannibalisation. 

It’s an SEO jungle out there

You’d think the big boys could get it right.

But Jon’s presentation showed that the bigger the site the more danger there is that it will create pages that compete against each other.

And the only winners in such battles are the competition.

The sad fact is that as sites get larger and pages multiply it can sometimes be really hard to see the wood for the trees.

And that’s when it strikes.

As drums pound in the distance, your site’s position on a search engine results page begins to bubble, bobble and fluctuate wildly.

And then it is gone.

Another victim of cannibalisation.

What is keyword or content cannibalisation?

One of the beauties of Jon’s talk was watching these large scales site’s search positions bubble and bobble wildly before they dropped completely.

We even got to see the competing pages from their own site sneak up and attack.

This was search engine results page forensics in action.

Look at easyJet. (We’ve kept the corporate orange for our markup).

For the valuable search term ‘flights to Liverpool’ the site lost its high ranking after some ominous bubbling and ended up struggling to maintain a place on page one.

What happened?

The site bit off its own nose to spite its search result page’s place.

How do we know?

Let’s add in the tell-tale data trails of some other pages from the site.

As if from nowhere the cannibals appear – here no less than 12 competing pages were identified. They achieve rankings for the same search term but they do not support the ‘hero page’.

Instead they drag it irrevocably down.

Those early bubbles were signs that something was about to happen. In hindsight it’s a bit like the search engine was confused:

“Are you really the hero page?”

“Who are these other guys bubbling under?”

“Shall I stick with you?”

Cannibalisation occurs when those pages in supporting roles get above their station. They want to be the stars of the show but unfortunately the result is the whole film gets ruined.

Thankfully there is a simple solution.

Jon’s talk was punctuated by the cry “Stick a canonical on it” like it was some magical incantation that can be used to ward off the cannibals.

And it can.

The canonical tag identifies your hero page from others. It leaves the search engine in no confusion as to who the star of the show is.

We’ll show you how to use it in a moment.

Jon identified three main sources of content cannibalisation.

  1. Internal Cannibalisation
    From competing pages (as in the example above)

  2. Subdomain Conflict
    From duplicate content held on different versions of your site (e.g. and

  3. International Conflict
    From duplicate content held on different international versions of your site (e.g. and


In praise of the Canonical tag

This rather handy piece of code can also be used whenever you have duplicate content on your site.

For instance duplicates can be...

  • Created at URL level by those pesky backslashes:
  • Created at subdomain level by that missing www:

  • Created by other subdomains:
    As in the example above for NatWest
  • Created by international versions of your site:
    As in the mysite example above

  • Created by similar pages that are competing against your hero page:
    As in the easyJet example above

It should be noted that as much love as we should be giving the Canonical tag there are other handy weapons in fighting off the cannibals.

These include making sure external links are pointing to your hero page and that this page also has more internal links. You have to give the star respect.

Here’s how you can pay dues with the Canonical.

The tag is part of the HTML head of a web page.

This tells the search engine that the page it appears on should be treated as if it were a copy of Furthermore it tells it that all of the links and content metrics this page gains that these should be given to the star of the show: your hero page.

You can find more details on Canonicals here.

The lion sleeps tonight

Cannibalisation is not just a problem for the big boys.

The smallest site can introduce duplicate content as a result of the process of designing a new site. The smallest site can add content that competes against itself for search positions.

The Canonical tag can help us all sleep a little sounder in the SEO jungle.

Until those bubbles start simering once more... 

If you are interested in learning more about the effects of internal canabilistation and if your website is effected then contant Pi Datmetrics and they'll book you in for a free demo.

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