Canonicalization Definition

What is canonicalization?

Canonicalization is the process of selecting the best URL when there are multiple choices available. This is a single line of code that tells search engines which page should be treated as the primary version.

Let's consider an example:

Suppose you have several URL options such as:


...and others, and all of those URLs show the exact same content. Your canonical tag chooses a primary or "canonical" URL that communicates to search engines about the specific URL version you want displayed in search results.

This also prevents duplicate content and cannibalization issues. Sometimes, duplicate content is required, and a canonical tag ensures that it doesn't hurt you or confuse people or search engines.

To break it down, it's like advising the search engines that "Among all these similar-looking pages, this one holds the utmost significance. Please give it due importance when indexing and showcasing results."

Here's another description of canonicalization:

"Canonicalization serves as a technique to resolve the problem of duplicate content and unify link signals for alike or identical content. By identifying the "canonical" or "preferred" webpage version, website owners can guarantee that search engines recognize and index their chosen URL."

This procedure is essential for Search Engine Optimization (SEO) as it simplifies search engine operations for crawling and indexing, stopping the scattering of page ranking and ensuring that all link equity points towards the canonical URL. It also improves user experience by guiding users toward the most important and regularly updated page version.

How Can I Use Canonicalization to Help My SEO?

By specifying a canonical URL for pages with similar or duplicate content, you can direct search engines to index the version of the page that you deem most important. This consolidation of link equity can boost the ranking power of the canonical page, as all signals from duplicate or similar pages are unified into one source.

This can also eliminate thin or redundant pages, giving greater weight to the pages that need it the most. If you're continually showing Google the same page dozens of times, or you have thousands of low-value sub-pages, Google might be indexing all of them and wasting your crawl budget. This also waters down your average page quality. But, if those pages are all smaller parts of a larger parent page, adding a canonical tag and providing some much-needed clarification to Google will strengthen your site in the process.

To implement canonicalization, you would add a rel="canonical" link element to the <head> of your duplicate web pages, pointing to the URL you wish to be the authoritative version. For instance, if " " and "" show the same content, you can choose one as the canonical URL, and Google will show the one that you chose in the search results.

How Can Canonicalization Hurt My SEO?

If misused, canonicalization can negatively impact your SEO efforts. Incorrectly assigning the canonical tag can lead to the wrong page being indexed and ranked, which could hide valuable pages from search engine results.

For example, if the canonical tag points to a less relevant or outdated version of your content or a page that has nothing to do with your page content, you may miss out on organic traffic that the more relevant page could have attracted. A canonical basically says, "Don't index me, index this page instead, which is the main page."

So, if you put that on a page that shouldn't have a canonical pointing to that page, it will reduce its search visibility, which in turn hurts your SEO.

Another issue is setting multiple canonical URLs for a single page or not having a self-referential canonical tag on the canonical version of the page. This can confuse search engines as to which page should be the source of truth, diluting the ranking power and possibly leading to none of the pages being indexed properly. If canonical tags are implemented inconsistently across a site (like using them on some duplicate pages but not others), it could lead to partial indexing of your content, and you'll end up with a fragmented presence in the SERPs.

Always ensure your canonicalization strategy is comprehensive and reflects the logical structure and hierarchy of your site's content.

Will Google Always Show My Canonical?

No. Google may not always show the URL you've picked as the main one in search results. These will show up in Google Search Console as "Duplicate, Google chose different canonical than user."

Different Canon

The main tag is more of a suggestion to Google, not a must-follow order. Google may decide whether to consider it. But if it finds another URL that might be a better fit than the main one, guess what? Google may go for that URL instead. This happens if Google decides that the content on the picked main page is quite different from the copied ones. Believe it or not, this can also happen if the main page can't be reached, has redirection problems, or if the copied pages have more content or get new things more often. It's really important to make sure that your main page is the best possible copy of the set, is high-quality and is easy to reach.

What Does The Canonical Tag Look Like?

The canonical tag is an HTML element, and it looks like this:

<link rel="canonical" href=""/>

It's put in the top section of an HTML document. Now, this is to let the search engines know about the main or primary version of a webpage. The href bit points to the webpage address of the page you want search engines to see as the main one and include in search results. Pretty easy, right?