Ever seen the term “canonical tag” and not understood what it meant? It sounds technical, but it’s actually pretty simple once you see what it does.

What is a Canonical Tag? (SEO Basic Explained) - YouTube thumbnail

What is a Canonical Tag?

A canonical tag, written as rel="canonical", is a link element that helps search engines identify your preferred version of a page when multiple URLs have identical or very similar content.

In simpler terms, it tells search engines, “This is the version I prefer you to index and show in search results.” Google treats rel="canonical" as a strong signal, not an absolute rule, so it can still choose a different URL when other signals disagree. That mismatch can produce statuses such as duplicate without user-selected canonical in Search Console.

For example, the canonical tag for your main blog page might look like this:

<link rel="canonical" href="https://yourblog.com/main-page/" />

Good news if you’re on WordPress: most SEO plugins, including Yoast and Rank Math, add self-referencing canonical tags automatically. You probably do not need to add them manually, but a misconfigured tag can cause Google to select an unexpected URL as canonical.

Why Are Canonical Tags Important?

  1. Clarify Duplicate URLs: Google chooses a canonical URL when it finds duplicate or very similar pages. Your canonical tag gives it a clear preference, though Google can choose a different version.
  2. Consolidate Ranking Signals: When backlinks point to different versions of the same page, canonicalization can help Google consolidate signals on the representative URL.
  3. Improve Crawling Efficiency: Google generally crawls canonical pages more often than duplicate versions. This matters most on larger or technically complex sites with many duplicate URL variations.

Best Practices for Using Canonical Tags

  1. Use Absolute URLs: Always use the absolute URL in the canonical tag, not the relative URL. For example, use https://yourblog.com/main-page/ instead of /main-page/.
  2. Self-Canonicalize: Even if a page doesn’t have any duplicates, it’s still a good practice to include a self-referencing canonical tag. This helps to avoid any confusion for search engines.
  3. Be Consistent: Make sure that the URL used in the canonical tag is consistent across the site. For example, if your site uses https, make sure that the canonical tag also uses https.

Common Mistakes to Avoid

  1. Canonical Chains: A canonical chain occurs when Page A references Page B as the canonical, and Page B references Page C as the canonical. Always point the canonical tag directly to the main version of the page.
  2. Multiple Canonical Tags: There should only be one canonical tag on a page. If there are multiple canonical tags, search engines might ignore them.
  3. Wrong Canonical Target: A canonical tag is not a redirect, but pointing a post at the wrong URL sends a strong and confusing signal. Google may ignore the tag or select the wrong URL for search, so always verify the target.

Do not use noindex as a substitute for a canonical tag on duplicate pages you want consolidated. A canonical expresses which version you prefer; noindex removes a page from search.

Quick Way to Check Your Canonical Tags

If you have the RightBlogger Chrome extension, you can quickly check whether a page’s canonical tag matches its URL. For Google’s final decision, use URL Inspection in Search Console to compare the user-declared canonical with the Google-selected canonical.

For most WordPress bloggers, canonical tags are handled automatically by your SEO plugin. But if your traffic suddenly drops on a specific page, a broken canonical tag is one of the first things to check.