Learn SEO: The Canonical Tag

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The canonical tag informs search engines, which, between several pages, is the master one. Using a canonical tag can help avoid duplicate content errors. 

The canonical snippet contains a URL to point to the page, which is considered the master. 

<link rel="canonical" href="https://example.com/"/>

Even though search engines are smart enough to figure out the contents of your page, duplicate content is still a massive problem for them. And for a good reason. 

For a search engine, any instance of a URL equals a different page. So example.com, example.com/home, or example.com/index.html, can cause duplicate content errors if they all exist since engines see them as separate pages even though you would consider them the same.

Similarly, eCommerce websites often suffer from duplicate content issues either because they have multiple very similar or identical products living in separate URLs as well as filters that generate hundreds or thousands depending on the magnitude of the site, unique URLs.

Best use of canonicals

There is a lot of confusion online when it comes to canonicals. Unfortunately, there is no one size fits all for canonicals, but here’s a list of things that you should consider when using canonicals.

Canonicals can self-reference

A canonical can be self-referencing, which means that a canonical tag that is contained in the head of the example.com can point to example.com. For the past few years, a common practice has been to add a self-referencing canonical tag at every page by default.

self-referencing canonical example

Dynamic Pages Canonicalization

As mentioned before, in the modern web environment, dynamically created pages are almost everywhere and can cause massive issues if they are not properly handled.

Examples of this could be a page generated by filters or facets used in an eCommerce product listing pages. 

Here are a few examples of dynamically created pages that can pass as duplicate

Be careful what you canonicalize

A canonical is a strong signal for search engines. That means that if you use it right, it can help your website but can hurt your website if you misuse it. 

One of the most common mistakes with canonicalization is using a canonical that points to another page when they should be self-referencing or self-referencing while they should aim to another.

Since no one rule fits all with canonicals, you need to identify the right opportunities depending on the situation. 

Warning: Google might pick a canonical, which is different than what you selected. Take that as a hint that maybe the canonical you’ve chosen didn’t make a lot of sense for them, and they found a page that they consider more suitable for the user query or there was an issue with your implementation.

That can lead to unwanted behavior such as 

  • Search engines crawl the master page less frequently since they consider it a duplicate page.
  • You’ve spent a lot of marketing budget on a page that ranks lower than a page you didn’t want to rank at all
  • Search engines do not even index the main page.

All of the above are highly possible, so make sure you understand the risks and benefits of using canonical tags.

How to ensure Google will pick the right canonical tag

Google is using several factors to identify what a page is all about. After crawling your site, they might locate several similar pages. Even though you might have a canonical to consolidate all of them into one, Google might still pick a different canonical for you.

A canonical is just one of the many signals they use to identify the main page of a subject. Here are a few tips on what you should do if Google selects a different canonical than the one you wanted. 

  • Make sure you include the master page in the sitemap.
  • Self-reference your main page’s canonical tag.
  • Canonicalize the rest of the pages to your main page.
  • Remove the canonicalized pages pointing to the main page from your sitemap. 
  • Main sure that your main page is adequately optimized. 
  • HTTPS is a strong signal of an optimized page, so make sure your site is using HTTPS over HTTP.
  • Ask Google to recrawl your page using GSC.

How to edit your canonical tag

Like the <title> tag or the meta description tag, your canonical tag is placed at the <head> section of your site. In most cases, changing it is straight forward since plugins like Yoast, Rank Math or All in One SEO can help you modify your canonical on a page to page basis. 

Similarly to WordPress, Shopify and Magento have their SEO plugins (paid or free) that offer the same functionality. 

If you are using a more static approach changing the template of your page is also an option. 

The canonical tag is most frequently found at the top of your <head> section and most often near the rest of the SEO meta tags. 

Canonical Tag in Head section with red arrow

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