What are Canonical Tags? How to Use Them on Your Website?

The canonical tags are HTML elements that are used to identify the primary or preferred version of a webpage. It is important for SEO purposes because it helps to prevent issues that may arise from duplicate content on your website. In fact, the canonical tags have been around since 2009, when Google, Microsoft, and Yahoo joined forces to create it as a solution to the problem of duplicate content. Despite its importance, it can sometimes be confusing to properly understand and use the canonical tag.

This article will cover what canonical tags and URLs are, canonicalization signals and the proper way to use them, the importance of canonical tags in SEO, and general guidelines for using canonicalization methods.

We will discuss these topics in depth, including the purpose of canonical tags and URLs, how to signal canonicalization to search engines, and best practices for implementing canonicalization methods on your website. Additionally, we will delve into the role that canonical tags play in search engine optimization and how following these guidelines can help to improve the visibility of your website in search results.

What are Canonical Tags?

A canonical tag is an HTML meta tag snippet used to educate the crawlers about the primary page that you want to be indexed or considered for indexing in case you have similar content on two different URLs.

This helps in handling the content duplicacy concern that can impact your website’s performance.

Furthermore, a Canonical tag is inserted into the HTML section. It must be added to the secondary page, and the URL reference in href should be of the primary page.


To mark a duplicate page with a rel=”canonical” link tag, add the below snippet in the section of the secondary or duplicate page. And, point the URL to the Primary page URL.

<link rel="canonical" href="https://example.com/dresses/green-dresses" />


In case, a canonical page has a mobile variant, add a rel=”alternate” link to it for pointing to the mobile version of the web page:

<link rel="alternate" media="only screen and (max-width: 640px)"  href="http://m.example.com/dresses/green-dresses">

Related: How to Increase Domain Authority for Your Website?

What are Canonical URLs?

It is the URL of the page that a search engine thinks is the most representative and important of a set of similar or duplicate pages on your website.

If you have a bigger website, it can often be tough to prevent pages from becoming duplicates. In these cases, the canonical URL plays an important role as a technical solution for duplicate content.

For example:

If you have an eCommerce website where the products are attached to two or more categories. You will have a similar URL as below.


Here, you can see that these two category URLs are duplicates and might list out the same products. So, in this case, you need to find the primary URL that you would like Google or Bing Search Engine to crawl and index and add canonical to the other URLs or pages.

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How to Define a Canonical URL?

In general, there are five known methods to implement canonical URLs which are also known as canonicalization signals.

  • HTML Tag: rel=canonical tag
  • HTTP header: rel=canonical
  • Sitemap
  • 301 redirect

Let’s now understand them in detail.

1. HTML Tag: rel=canonical tag

“rel=canonical tag” is the most simple way to add a canonical reference to a webpage URL. You can simply use the below code in the section of the secondary or duplicate pages:

<link rel=“canonical” href=“{Your primary page URL }” />

For example:

Suppose you have two different URLs



You need to add the following canonical tag to any of the pages:

<link rel=“canonical” href=“https://dreamwebmarketing.com/seo/digital-marketing/” />

Pros of an HTML canonical Tag:

HTML canonical tags can be used to map an infinite number of duplicate pages.

2. HTTP header: rel=canonical

In the case of a PDF document, you don’t use canonical tags in the header section of the web page. The “HTTP header” is used there to set canonicals.

The below piece of code can be added to your hosting .htaccess.

<Files “file.pdf”>
Header add Link “<http://www.example.com/page.html>; rel=\”canonical\””

Here, the above snippet of code will add an HTTP Header to the PDF file which will point to an HTML page with the URL of/page.html.

Pros of an HTTP header (rel=canonical):

It doesn’t increase the size of the page and can map for an infinite number of similar pages.

3. Sitemap

According to Google, you just need to submit and specify the canonical URL of the web page in the sitemap. You need to avoid non-canonical URLs from submitting in the sitemap.

Note: Google doesn’t guarantee that it will consider the sitemap URLs to be canonical, however, it is a simple way of defining canonicals for a big site.

Pros of submitting an URL in Sitemap:

It’s quite easy to submit a URL in the sitemap and maintain them for a large site.

4. 301 Redirect

You use 301 header redirect when you want to get rid of multiple duplicate pages.

Steps to redirect URLs through Web Hosting:

  • Log in to your Hosting > 301 redirects.
  • Add the old URL in the “Old Path” field (you want to redirect to another URL).
  • Add the new URL in the “Redirect to Page” field (you want to redirect on).
  • Add the redirect path and publish your site.
  • Test the old URL on search engines if it is getting directed to the new one.

For a WordPress website, follow the below steps:

Download and install the WordPress Redirections plugin.


Or, if you’re using the Yoast Premium SEO plugin, you will have the “Redirections” module by default.

Here in this example, we have used the redirections plugin to demonstrate its use.

First of all, log in to your WordPress Website backend.

  • Through Dashboard Click on Tools > Redirections
  • Source URL: Type the URL you want to redirect from
  • Target URL: Type the URL you want to redirect to
WordPress: To Add A New Redirection
WordPress: To Add A New Redirection

Also read: The Ultimate Guide on the Benefits of Building Link for SEO

What are Canonicalization Signals?

Canonicalization is the process of identifying and selecting the primary or preferred version of a webpage or piece of content. In addition, we often use this to solve issues related to duplicate content on a website, as search engines may penalize a site for having multiple pages with similar or identical content.

There are several ways to signal to search engines which version of a webpage is the primary or preferred one. One way is to use the canonical tag, as mentioned earlier. This is an HTML element that we need to place in the head section of a webpage and looks like this:

<link rel="canonical" href="https://www.example.com/primary-page">

Another way to signal canonicalization is through the use of the rel=alternate hreflang tag, which you use to indicate to search engines that there are alternative versions of a webpage available in different languages or for different regions. This can help search engines to understand which version of a webpage Google should display to users in different locations.

In addition, using 301 redirects can also signal canonicalization, as it indicates to search engines that a webpage has been permanently moved to a new URL. This can be useful for consolidating multiple pages with similar or identical content under a single URL.

It is important to properly signal canonicalization to search engines in order to ensure to display the correct version of a webpage and to avoid any potential SEO issues related to duplicate content.

Related: How to Increase Domain Authority for Your Website?

What are the Importance of Canonical Tags?

We recommend canonical tags because Google uses the canonical pages as the main source pages to crawl, index, and evaluate content & quality. The Google search result usually depends on the canonical pages, until or unless similar or duplicate pages suit better for a user.

Let’s know some more benefits of using canonical tags.

1. The canonical tag is important to let search engines understand which URL you want people to see in SERPs.

2. It’s beneficial to consolidate link signals for duplicate web pages.

3. Moreover, we use it to simplify tracking metrics for a single topic or product.

4. You also use canonical tags for managing syndicated content.

5. You also can avoid spending crawling time on similar pages.

How Does a Canonical Tag Help in SEO?

Canonical tags provide search engines with great control over similar content. It is a duplicate content that has a negative impact on SEO.

It’s very important to apply a canonical tag on the home page so that you and user can access this through different URLs. And, it means a set of versions of your homepage URL will compete with one another for Google search results.

Here, using canonical tags is the simplest way to resolve such complex issues. Canonical tags are very helpful for handling duplicate product pages on e-commerce websites.
Hence, by using canonical tags, you eliminate certain URLs and lower the competition for search results.

Also read: How to Optimize an Image for SEO?

General Guidelines for Using Canonicalization Methods

Here are 6 most important general guidelines for using canonicalization methods:

1. Identify all pages on your website that have duplicate or similar content. This may include pages with similar titles or descriptions, or pages that we publish under multiple URLs.

2. Choose the primary or preferred version of each page, and make sure that it is the most complete and up-to-date version. Additionally, this will typically be the version that you want search engines to index and display in search results.

3. To signal to search engines which version of each page is the primary one, use the canonical tag. Additionally, we replace in the head section of each page, and should point to the URL of the primary version.

4. To indicate to search engines that there are alternative versions of a page available in different languages or for different regions, use the rel=alternate hreflang tag. So, this can help search engines understand which version of a page it should display to users in different locations.

5. To consolidate multiple pages with similar or identical content under a single URL, use 301 redirects. Moreover, this can help prevent confusion and ensure that search engines are only indexing a single version of each page.

6. Monitor your website regularly to ensure that all canonicalization methods you implement correctly and are still necessary. As your website evolves, you may need to adjust your canonicalization strategy to ensure that it continues to meet your needs.


Canonical tags are very necessary to use for your web pages or website. Using them effectively can lower competition among other pages of your website. Therefore, through canonical tags, you fix SEO issues and improve the performance of your website.


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