Understanding Canonical Tags

Canonical tags, also known as “rel=canonical”, are an HTML element that helps webmasters prevent duplicate content issues in search engine optimization.

Importance Rating of 8/10

They tell search engines which version of a page is the “canonical” or “preferred” one when multiple versions of a page exist (for example, if there’s a print version of the page, a mobile version, tracking parameters in the URL, or even just www vs. non-www versions).

A canonical tag is placed in the head section of the HTML of a web page, providing a reference to the canonical URL. Here’s an example of what a canonical link element looks like:

<link rel=”canonical” href=”https://www.example.com/preferred-page.html” />

For instance, if you have two similar pages with the following URLs:

  • https://www.example.com/page
  • https://www.example.com/page?tracking=true

You can add a canonical tag to both pages’ HTML to indicate to search engines that the first URL (without the tracking parameter) is the one you want to be indexed and rank in search results. This helps avoid issues of perceived duplicate content, which could dilute your ranking power or lead to one version of the page being indexed over another, less-desirable one.

In WordPress, canonical tags are often implemented by WordPress SEO plugins like Yoast SEO or All in One SEO Pack automatically. These plugins can intelligently generate the appropriate canonical URLs for your content, helping to ensure that search engines understand which pages are the originals and should be given priority in search results. However, webmasters should still regularly audit their canonical URLs to ensure they’re set correctly, especially in complex scenarios with numerous similar pages.

Here’s why they are so crucial:

  • Prevent Duplicate Content Issues: Search engines aim to provide unique content in their search results. Without canonical tags, search engines might consider different versions of the same content as duplicates, which can lead to indexing issues and dilute ranking signals.
  • Consolidate Ranking Signals: Canonical tags help consolidate link equity (the ranking power of external and internal links) to the preferred page. This is important for SEO as it ensures that all signals are directed to the canonical page rather than being split across multiple similar pages.
  • Control the Indexed Version: There are scenarios where the same content is accessible via multiple URLs. With canonical tags, webmasters can guide search engines toward the URL they want to appear in search results, thus maintaining a cleaner index.
  • Cross-Domain Content: Sometimes content is syndicated and published across different domains. Canonical tags can be used to point back to the original content on the primary website, helping to avoid penalization for duplicate content across domains.
  • Managing URL Parameters: Websites with dynamic parameters (e.g., for tracking or sorting) can end up with many URLs pointing to the same content. Canonical tags can prevent search engines from indexing each parameter-based variant.

How to Setup Canonical Tags


  • Use an SEO plugin like Yoast SEO or Rank Math that has built-in support for canonical tags. This automatically adds the tags.
  • Manually add canonical tag code in the head section of your theme’s header.php file. More work but full control. Source
  • Modify the rel=”canonical” tag directly in individual posts and pages from the editor to control page-specific values. Source


  • Canonical tags are automatically added to all Squarespace pages. Users don’t have to manually add them. Source
  • The canonical URL is set to the page URL by default. This can be changed in Page Properties. Source
  • Squarespace has sitewide canonical tag settings under SEO in Site Settings. Source


  • Canonical tags need to be manually added to theme template files like product.liquid or page.liquid. Source
  • Apps like Shopify SEO and Canonical Tags Manager can automatically handle canonical tags. Source
  • Canonical tags can be added to collection pages to choose the main URL. Source
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