WTF Is a Canonical Link?

A canonical link might sound like something holding a canon together. But it’s actually a really important part of search engine optimisation (SEO).

It is an element in the code of a web page that tells a search engine what the ‘original’ or ‘preferred’ version of a web page is. It prevents duplicate versions of the same web page appearing in searches, and can stop SEO penalties from affecting your search rankings.

A URL Can Have Many Versions

When you have a web page, you might see just one version of it. But there’s often many URLs pointing to the same page. For example:

  • http://www.mysite.com
  • https://www.mysite.com
  • http://mysite.com
  • http://mysite.com/index.php
  • http://mysite.com/index.php?p=106

To a search engine these all count as separate pages. They also only represent a fraction of what can appear on a website. An ecommerce site might have several different URLs for the same page. Each one might be created when someone specifies a certain currency, product type, rating, and so on. If your business operates in many different countries and you have country-specific URLs, then you will need to use canonical links.

Similarly, if you’ve used both upper and lower case when naming files and folders on your website’s content management system (CMS) then canonical links should be used.

Some websites have a separate version that’s mobile-optimised. You might have seen links like m.mysite.com for this dedicated mobile experience. In this case, a canonical link should be included to inform the search engine of the original content.

Why Does a Lack of Canonical Links Cause Issues?

There are a number of reasons why having too much duplicate content can cause your website SEO problems. Firstly, when you have a large number of URLs, a search engine might miss something important on your website. This is especially true when you have an online shop that may have hundreds, if not thousands, of URL variations.

Then there’s the problems that duplicate content poses to your SEO ranking. Lots of the same content can mean you drop down in rank or even get marked as potential spam.

Finally, without a canonical link directing a search engine to your original content, the search engine might pick up the wrong URL instead of the correct, original one.

What a Canonical Link Looks Like

When using canonical links, you should put the following within your html code on whatever web page it relates to:

<link rel="canonical" href="https://www.mysite.com/blog/article-title-goes-here">

To see the canonical link in real life, check out this post that originally appeared on pebble magazine:

https://pebblemag.com/magazine/eating-drinking/silo-the-uks-first-zero-waste-restaurant

This was then syndicated to Eco & Beyond:

https://www.thefoodrush.com/articles/behind-the-bins-at-silo-the-uks-first-zero-waste-restaurant/

With the canonical URL in the page’s source code shown as:

<link rel="canonical" href="https://pebblemag.com/magazine/eating-drinking/silo-the-uks-first-zero-waste-restaurant" >

This means that any traffic, shares or links back to the post on Eco & Beyond automatically have their SEO benefits transferred to the original (canonical) source: pebble magazine.

When to Use Canonical Links

If your website has a lot of variations and many pages, then using canonical links can help your SEO. They allow you to control what web pages appear in search results. But before introducing canonical links on your website, there’s work to be done. You must take the time to figure out what web pages will benefit and which pages are your original pages.

If you’re already using canonical links it’s worth checking your strategy from time to time. This will ensure all the right pages are being indexed by search engines.

If you’re using a content management system like WordPress, SquareSpace, Shopify and many others it’s likely that canonical links have already been taken care of. If you’re a WordPress user and want to manually set canonical links, this can be done using the very handy Yoast SEO plugin.

canonical link yoastWith today’s saturated search results, having the right canonical links can help your website stand out amongst the noise.