How To Use the Canonical Link Element for Duplicate Content

If you want to avoid duplicate content issues, using the canonical link tag can help. This technical SEO best practice is fairly straightforward, and in this article, I’ll talk about why and when you should use it, and tips on how to get started.

• What Is a Canonical URL?
• When to Use a Canonical URL
• How to Use the Canonical Link Element
• Canonicalization FAQs
• FAQ: How can I effectively use canonical URLs to prevent duplicate content issues and improve my SEO?

What Is a Canonical URL?

A canonical URL is a webpage that is the best representative of a group of duplicate or near-duplicate webpages.

The canonical link element helps solve duplicate content issues by signaling to search engines like Google which webpage is the original or best pick out of a group of pages that are duplicate or near duplicate.

Google defines canonical URL as:

“A canonical URL is the URL of the best representative page from a group of duplicate pages, according to Google. For example, if you have two URLs for the same page (for example: example.com?dress=1234 and example.com/dresses/1234), Google chooses one as canonical. Similarly, if you have multiple pages that are nearly identical, Google can group them together (for example, pages that differ only by the sorting or filtering of the contents, such as by price or item color). (You might hear the term “canonical page” used occasionally, but that is technically incorrect, as it is a specific URL that is actually canonical.)
The canonical can be in a different domain than a duplicate (such as en.example.com and fr.example.com).”

The hope is that the canonical URL is the webpage that receives the SEO benefit. And while you can indicate a canonical URL, Google states that none of them are required:

“While we encourage you to use these methods, none of them are required; your site will likely do just fine without specifying a canonical preference. That’s because if you don’t specify a canonical URL, Google will identify which version of the URL is objectively the best version to show to users in Search.”

Google goes into more detail on how it chooses the canonical URL in this video:

In the video, Google’s John Mueller states that Google picks the canonical URL by following two general guidelines:

1. Which URL does it look like the site wants Google to use?
2. Which URL would be more useful for the user?

When in doubt, you can use the URL Inspection tool in Google Search Console to find out which page Google considers the canonical.

When to Use a Canonical URL

A canonical URL is for solving duplicate content issues. These duplicate content issues could be on your site or they could be shared with other websites.

Duplicate content is an SEO no-no, and you can learn more about that in: Is Duplicate Content Bad for Search Engine Rankings?

Some reasons to use the canonical link element:

• Specify which webpage you want in the search results.
• Consolidate link signals for similar or duplicate webpages.
• Simplify tracking methods for a product or topic.
• Preserve crawl budget.

It used to be that the canonical link element was used often if you were to syndicate content across third-party publishers.

Today, Google says:

“The canonical link element is not recommended for those who wish to avoid duplication by syndication partners, because the pages are often very different.

The most effective solution is for partners to block indexing of your content.

For more, see Avoid article duplication in Google News, which also has advice about blocking syndicated content from Google Search.”

Google gives a list of do’s and don’ts when it comes to canonicalization in its help file:

• Don’t use the robots.txt file for canonicalization purposes.
• Don’t use the URL removal tool for canonicalization. It hides all versions of a URL from Search.
• Don’t specify different URLs as canonical for the same page using different canonicalization techniques (for example, don’t specify one URL in a sitemap, but a different URL for that same page using rel=”canonical”).
• We don’t recommend using noindex to prevent selection of a canonical page within a single site, because it will completely block the page from Search. rel=”canonical” link annotations are the preferred solution.
• If you’re using hreflang elements, make sure to specify a canonical page in the same language, or the best possible substitute language if a canonical page doesn’t exist for the same language.
• When linking within your site, link to the canonical URL rather than a duplicate URL. Linking consistently to the URL that you consider to be canonical helps Google understand your preference.
• Specify a canonical page when using hreflang tags. Specify a canonical page in same language, or the best possible substitute language if a canonical doesn’t exist for the same language.
• When linking within your site, link to the canonical URL rather than a duplicate URL. Linking consistently to the URL that you consider to be canonical helps Google understand your preference.

Also note that “Google prefers HTTPS pages over equivalent HTTP pages as canonical, except when there are issues or conflicting signals.”

For even more on canonicalization and when to use it, Google myth-busts some common beliefs about canonicalization in the following video:

In that video, they cover:

• Canonicalization is not a topical grouping (0:00)
• The most common canonicalization myths (1:29)
• Is canonicalization a directive or a signal for Google Search? (2:01)
• Should canonicalization be used as a redirect? (3:08)
• What are the actual factors for duplication and deduplication? (4:25)
• Site’s preference for the canonical URL vs user’s preference (7:33)
• Canonicalization vs unique content on pages with a canonical tag (08:59)

How to Use the Canonical Link Element

You can specify a canonical URL with rel=”canonical” in two ways:

1. Add a rel=”canonical” link element to the <head> section of the duplicate (non-canonical version) of each webpage.
2. Indicate the canonical version of a URL by using a rel=”canonical” HTTP header.

Google gives a list of pros and cons for each execution type here.

Although Google gives multiple recommendations, they explain that you should choose one type of canonicalization method and stick with that.

Using more than one type of canonicalization method will be more prone to errors than using a single type of canonicalization method.

1. Adding a rel=”canonical” Link to the <head> Section of the Duplicate (Non-Canonical Version) of Each Webpage

To tell the search engines when a page is a duplicate of another page, you can use the rel=”canonical” link tag on all the duplicate pages, indicating which page is the canonical URL.

Let’s look at an example. To specify a canonical link to the fictional URL: http://www.example.com/product.php?item=swedish-fish, you’d create a <link> element as follows:

<link rel=”canonical” href=“http://www.example.com/product.php?item=swedish-fish”/>

You’d then copy this link into the <head> section of all non-canonical versions of the page, such as http://www.example.com/product.php?item=swedish-fish&sort=price.

If you publish content on both http and https, such as the following example:

http://www.example.com/product.php?item=swedish-fish and https://www.example.com/product.php?item=swedish-fish, you’d specify the canonical version of the page as well.

Create the <link> element as follows:

<link rel=”canonical” href=”http://www.example.com/product.php?item=swedish-fish”/>

Add this link to the <head> section of https://www.example.com/product.php?item=swedish-fish.

2. Indicating the Canonical Version of a URL by Using a rel=”canonical” HTTP Header

Adding rel=”canonical” to the head section of a page is useful for HTML content, but it can’t be used for PDFs and other file types indexed by Google.

In these cases, you can indicate a canonical URL by responding with the link rel=”canonical” HTTP header, like this (note that to use this option, you’ll need to be able to configure your server):

Link: <http://www.example.com/downloads/white-paper.pdf>; rel=”canonical”

Canonicalization FAQs

Here are a few common questions we get about canonicalization and their answers:

Is rel=”canonical” a suggestion or a directive?

The rel=”canonical” attribute is a hint or suggestion, not a directive.

The rel=”canonical” lets site owners suggest the version of a page that Google should treat as canonical. However, rel=”canonical” is a strong signal that the specified URL should become canonical.

Google will take this into account with other signals when determining which URL sets have identical content, and when calculating the most relevant of these pages to display in search results.

The rel=”canonical” attribute should be used only to specify the preferred version of pages with identical content (although minor differences such as sort order are OK).

For instance, if a site has a set of pages for the same model of dance shoe, each varying only by the color of the shoe pictured, it may make sense to set the page highlighting the most popular color as the canonical version so that Google may be more likely to show that page in search results.

Can Google follow a chain of rel=”canonical” designations?

Yes, to some extent, but to ensure optimal canonicalization, our recommendation is to update links to point to a single canonical page.

What’s the difference between applying a 301 redirect and using a canonical link element to avoid duplicate content?

301 redirects and canonical tags are both used to tell search engines about multiple versions of a web page.

301 redirects are used when a page has moved permanently, while canonical tags are used when there are multiple versions of a page.

Here are some differences between 301 redirects and canonical tags:

• 301 redirects are a status code that tells search engines and users that a page has moved permanently.
• 301 redirects remove the page from the index and pass any SEO credit to the new page.
• 301 redirects send users to the new location of a page.
• The canonical tag tells search engines which page to show in search results.
• Canonical tags are used to prevent problems caused by duplicate content appearing on multiple URLs.

Google gives some examples of when you’d use 301 redirects, here.

Can we use relative URLs in the canonical link element?

Google suggests using absolute URLs rather than relative URLs with the rel=”canonical” link element.

Even though relative paths are supported by Google, they can cause problems in the long run (for example, if you unintentionally allow your testing site to be crawled) and thus are not recommended).

(Read more on relative vs. absolute URLs.)

Does rel=”canonical” work if the URLs are different?

No, the canonical link element is only effective if the pages are duplicates or near duplicates.

If the pages are different, Google will disregard the canonical link element and consider the URLs as two different pages

To sum up, it’s worth taking the time to implement a canonical URL if you think you might run into duplicate content issues. Your SEO program will thank you.

Duplicate content issues affecting your SEO? Our SEO experts can help. Schedule a free 1:1 consultation with us today.

FAQ: How can I effectively use canonical URLs to prevent duplicate content issues and improve my SEO?

Canonical URLs play a crucial role in website optimization, enabling you to address duplicate content problems and enhance your SEO efforts. Understanding their purpose and implementing them correctly can make a significant difference in your search engine rankings.

So, let’s discuss the best practices for their effective usage.

Defining canonical URLs
Canonical URLs are HTML tags that inform search engines about the preferred version of a webpage when there are multiple versions with similar content. By specifying the canonical URL, you steer search engines in the right direction, ensuring they attribute the desired SEO value to the chosen URL.

Why are canonical URLs important?
When search engines encounter duplicate content, they can become confused about which version to rank in search results. As a result, your website’s SEO may suffer, and traffic may be divided among different pages. Canonical URLs address this issue by consolidating authority and ensuring that only one version is considered for ranking.

Implementing canonical URLs correctly
To effectively use canonical URLs, follow these steps:

• Identify duplicate content: Analyze your website to find duplicate content pages that may cause confusion among search engines. Tools like Google Search Console and third-party SEO platforms can help with this task.
• Choose the preferred version:Determine the primary version of the page that you want search engines to rank.
• Add the canonical tag: Insert the canonical tag in the head section of the duplicate content pages, specifying the preferred version’s URL.

Best practices for canonical tags
To make the most of canonical URLs, consider these tips:

• Consistency is key: Maintain consistency by using canonical tags uniformly throughout your website. Ensure all canonical URLs point to the same page when different versions exist.
• Use appropriate directives: Utilize the rel=canonical attribute to specify the canonical URL.
• Include self-referencing canonical tags: Even if a page has no duplicate versions currently, it’s good practice to include a self-referencing canonical tag to ensure consistency in case duplicates arise in the future.

Buyer intent search terms
When optimizing your content, keep in mind the buyer intent search terms related to canonical URLs. Some examples include “best practices for canonical URLs,” “canonical tags implementation,” and “how to prevent duplicate content using canonical URLs.”

Benefit of canonical URLs for SEO
By using canonical URLs correctly, you can consolidate the SEO value of duplicate content pages into one preferred version. This helps search engines understand your site structure better and keeps your rankings focused on the desired URL.

Regularly monitor duplicate content
Keep an eye on your website’s duplicate content by using SEO tools that send alerts when new instances are detected. This proactive approach ensures you maintain control over your site’s SEO performance.

Canonical URLs are an essential tool in preventing duplicate content issues and enhancing your SEO strategy. By correctly implementing canonical tags, you guide search engines toward the preferred version and consolidate SEO value. Stay vigilant, monitor duplicate content regularly and optimize your website for improved search engine rankings.

Step-by-Step Procedure:

1. Identify duplicate content pages on your website.
2. Choose the preferred version of the page.
3. Insert the canonical tag in the head section of duplicate content pages.
4. Specify the preferred version’s URL in the canonical tag.
5. Ensure consistency by using canonical tags uniformly on your website.
6. Use the rel=canonical attribute to specify canonical URLs.
7. Include self-referencing canonical tags on pages with no duplicates.
8. Optimize your content for buyer intent search terms related to canonical URLs.
9. Consolidate the SEO value of duplicate content pages into the preferred version.
10. Maintain a clear site structure for search engine understanding.
11. Regularly monitor duplicate content using SEO tools.
12. Receive alerts for new instances of duplicate content.
13. Take proactive actions to resolve and prevent duplicate content issues.
14. Stay updated with the latest best practices for canonical URLs.
15. Continuously optimize your website for improved search engine rankings.
16. Implement changes to canonical URLs whenever necessary.
17. Regularly review and refine your SEO strategy.
18. Stay knowledgeable about search engine algorithm updates.
19. Attend SEO conferences and join industry forums for expert insights.
20. Collaborate with SEO professionals to improve your website’s performance.

Implement the steps outlined in this article to prevent duplicate content issues, optimize your website and improve search engine rankings.