What Is Canonicalization & Why Should I Care?

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Canonicalization is the easiest way to stop duplicate content appearing in search engines.

Adding “rel=canonical” tags to your page shows search engines you’re aware of the duplicate content and you don’t want it to be added to their index.

This allows you to proactively avoid the negative side-effects of having duplicate content.

How Does Canonicalization Work?

Sometimes there will be multiple URLs that give you access to very similar pages in terms of content.

When this happens, you need to implement canonicalization to avoid search engine confusion over duplicate content.

A common place where this happens is on your home page.

If you haven’t got things setup correctly, your homepage could be accessed from two different URLs.

One with a “www.” subdomain and one without.

That looks like this:

Although the URLs are different the content is exactly the same on each page.

This can create a problem for a search engine like Google. Why?

Firstly, it doesn’t know which of these pages in the right page.

It can’t tell from content which of these pages is the “correct” homepage for your website.

So, it doesn’t know which page it should rank.

Secondly, it sends a red flag to Google’s crawlers.

Your site has two pages that are exactly the same (also known as duplicate content), which Google doesn’t want to display.

This can lead to:

The way to stop this from happening is by using Canonicalization.

By adding the “rel=canonical” tags to your page you can tell Google not to index that page and to choose the other page you’ve not added a tag to.

That’s what canonicalization is and how it works…

But when should you use it, and how do you apply the tags?

When Should You Use Canonicalization?

When you run a website you can often generate duplicate links without even realising it.

Even a short addition like UTM tracking code in the URL can create a second version of the page.

Here’s a list of the most common places you’ll find duplicate content.

#1: URL Variations

If you’re using tracking or analytics software…

This can often create a problem with duplicate links.

For example:

A UTM tracking code for Google Analytics will result in two versions of the same link:

Also, if you have multiple versions of a page – like a PDF version or a direct duplicate to track affiliate sales – you may also encounter this problem.

These two links may lead to completely different areas of your site map:

But they contain the exact same information.

This is a duplicate content problem.

#2: Split Testing

When running split tests between different versions of a page you create duplicate content so adding canonical tags are mega important when setting these tests up.

For example when I decided to do some split testing on some new layouts…

I had 3 page layout URL’s

1. https://www.searchlogistics.com/seo/link-building/backlink-analysis/
2. https://www.searchlogistics.com/seo/link-building/backlink-analysis-2/
3. https://www.searchlogistics.com/seo/link-building/backlink-analysis-3/

So I set a canonical URL on these 2x urls-

To point to the master URL-

That way when Google crawled the other pages, they didn’t see them as duplicate content.

They followed the canonical link to the master page and recognised that as the main page and discarded the others.

#3: Product Pages

If your site contains product pages with links that point to different parts of that page, you’ll need to add canonical tags to them.

For example, one product page could have four different links pointing to the same page:

You would need to pick which is the master and then add canonical links from all of the other pages to point to the mater page you selected.

#4: HTTP vs HTTPS and WWW. vs Non-WWW.

As you saw in the introduction example…

How your site is setup can cause duplication errors depending on your setup.

Try loading each of these variations for your website in your browser-

If they don’t all redirect and end up on the exact same address (pay close attention to your browser address bar) then you have problems.

You can also use this Redirect Mapper tool to check if you are setup correctly-

The correct setup should have 3x URL’s with 1x 301 redirect and 1 URL with no redirect all ending with a final status code of 200.

If you don’t have that – it’s likely you have issue with duplicate content.

How To Manage Canonicalization With Yoast SEO

Yoast SEO is an absolutely awesome SEO Plugin for WordPress websites.

And it can be extremely helpful in performing canonicalization and to manage these links.

When the wordpress SEO plugin is installed, Yoast automatically indexes the primary URL and adds canonical tags to the rest of the links surrounding that page.

That means if you’ve set your URL to https://www.yourwebsite.com/blog/living-in-miami/.

It will only submit that page to be indexed. The rest will be tagged with canonical tags.

This might be all the support you need…

But what do you do when you don’t want this primary page to be indexed and would prefer a different version? Well, the Yoast SEO plugin can help with that too.

Open up the page you want to add a canonical tag to…

Head down to the Yoast SEO editor at the bottom of the page:

On the side bar select the “cog” at the bottom of the three options.

This will open the settings section of the tool but you only need to worry about this section:

In this box you’re going to enter the link you do want to have indexed in Google.

If you don’t fill this in it will revert back to the default permalink for the article – which is not always the link you want to have indexed.

So, only leave this box blank if the default permalink is definitely what you want to link back to.

All you do is copy and paste it into this box and then click the WordPress “update” button.

And there you have it, nice and easy!

Wrapping It Up

Duplicate content is bad for your search engine rankings.

Canonicalization is the process of adding canonical tags (“rel=canonical”) to a duplicate URL or page to ensure it isn’t indexed in Google.

You will often find duplicate links when:

You can easily manage this with the Yoast SEO plugin.

This automatically adds tags or allows you to set the indexable page yourself in the tool.

In the next section, we’ll be looking at how you can use Rich Snippets to your advantage.

Click here to learn what they are and how they work.