The Pure SEO Guide to URL Canonicalisation

URL canonicalisation is an essential part of any effective SEO strategy, allowing web developers to gain more control over their most important online content. Understanding how to use canonical tags correctly will be crucial to your success. Below, we explore how canonical tags work, how to use them correctly, and how to avoid canonical issues in SEO.

What are Canonical Tags?

The primary goal of a canonical tag is to prevent the issue of duplicate content. Page duplicates occur when different pages with the same (or very similar) content are accessible by multiple URLs.

If you want the most relevant version of a page to rank on SERPs (Search Engine Results Pages), adding a canonical tag to the page is a proactive solution. The canonical tag tells search engines which version of the page is the “master copy.” Essentially, it helps search engines understand which pages on your website are most important and which ones aren’t.

How Canonicalisation Affects Your SEO

To understand why canonicalisation matters, it’s important to understand why content duplication can be harmful.

If there is too much duplicate content on your website, search engines won’t know which page to crawl. This means your most important and relevant content may get lost. Content duplication can also be damaging to your site’s ranking ability. For instance, if multiple URLs appear on SERPs, users won’t know which one to click. Your page rankings will be diluted by different users clicking multiple URLs.

There are many instances where your website may have duplicate content, and often it is not intentional. Content duplication is particularly common amongst e-commerce websites, where multiple URLs lead to the same product page. Many website homepages may also have multiple URL variations.

Implementing canonical tags where appropriate can help to:

  • Direct traffic to preferred web pages – A canonical tag will help you to specify which page shows up on SERPs, thus driving more traffic to the desired page.
  • Manage syndicated content – When you publish syndicated content, multiple versions of the content may show up on search results pages. Adding a canonical tag will help you to control which version shows up on SERPs.
  • Control crawl time – You want search engine bots to spend time crawling your most important pages, instead of wasting time on duplicates.

SEO Best Practices for URL Canonicalisation

Canonical tags only work if they are applied correctly. But it’s all too common for web developers to make mistakes when implementing canonical tags on their websites. Let’s dive deeper into the SEO best practices for canonical tags:

Choose Canonicals Carefully

Canonicalising the wrong URL, too many URLs, or non-duplicates can be damaging to your website’s SEO. When choosing which URLs to canonicalise, stick to the following rules to ensure SEO success:

  • Be cautious of non-duplicates – When implementing a canonical tag, be sure that the page is actually a duplicate. For example, an article that spans multiple pages does not need to be canonicalised, because, in this instance, each page is not a duplicate of the other. Adding canonical tags where they are not necessary will only confuse search engines and harm your SEO.
  • Don’t over-use canonical tags – If multiple canonical tags are declared, search engines won’t understand which version is the “master” copy and may ignore all. When implementing a canonical tag, make sure you haven’t accidentally added an extra one where it shouldn’t be.
  • Canonicalise your most relevant URL – When choosing which URL to be the “master copy,” make sure it is the one that you want to rank. This may be the page with the highest link equity, keywords, and visitors.

Use Absolute URLs

Using absolute URLs is a vital part of the canonicalisation process. An absolute URL features every element of a “full” URL, including the HTTPS element, the www element, the domain name, and the .com element. This is different from relative URLs, which don’t include the full URL structure. Relative URLs only include the path, which is the information that comes after the domain.

An absolute URL looks like this: https://pureseo.com

A relative URL looks like this: /about/team

Absolute URLs contain all the information about a web page’s location. Implementing canonical tags in your absolute URLs will clarify for search engines where the page can be found and which is the preferred version.


Robyn has lived in New Zealand for 15 years, after living in Trinidad for most of her childhood. Since arriving in New Zealand, she has travelled most of the country, and has also travelled abroad to North America, Asia and Europe. In her free time, Robyn loves going to the beach, discovering new places to eat, and spending time with family.

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