What are Canonical URLs? Set Canonical properly to optimize SEO

As a site grows larger and larger, it is difficult to avoid overlapping pages. If you have 2 or more similar or similar pages and all qualify to rank for a certain keyword, it will be very difficult for search engines to distinguish which is the site to rank for. To solve this problem, you can choose a root URL also known as Canonical URL. For a deeper understanding of what Canonical URL is and how Canonical URL optimization Effective in SEO, find out with SEOVietNam now!!!

What are Canonical URLs?

Canonical URL is a technical solution to the problem of duplicate content on websites. It is defined as the primary version for pages that are similar or duplicate in content.


What is Canonical?

For example, you can have a product post attached to two categories and exist as 2 different URLs:

  • https://bestshoes.com/black-shoes/black-and-white-shoes/
  • https://bestshoescom/white-shoes/black-and-white-shoes/

Both of these URLs are about the same product and the content on each page is exactly the same or similar. Then, choosing a URL as the Canonical URL will help Google and other search engines know which version of the URL will be displayed on the search results.

Why use Canonical URL

As noted above, Canonical URL was developed to solve the problems of Duplicate content (Duplicate Content). When search engines view multiple pages with the same content, it encounters a situation: not knowing which is the original version, choosing which pages to index (index) and rank on search engines.


Google questioned it when it met Duplicate Content

Search engines like Google will need a cue to filter out duplicate results and provide a better user experience. Because Google knows that, no user wants to see the same content multiple times in different results pages. This only results in a bad experience when user queries are made with the intent of finding more information.

Now you can easily solve these problems and generate lasting SEO results using Canonical URLs.

How to Identify a Canonical URL

Checking Canonical URLs can be done in 2 basic ways: view-source and using tools MozBar.

1. View-source

A Canonical URL can be identified in HTML through the rel=”canonical” attribute tag. It is an element that only search engines see and internet users are not affected by it. In most browsers, you can easily right-click, select “View Page Source” or press Ctrl + U to open the view-source. The canonical tag in the is displayed as shown:


Check canonical url with view-source

2. Using MozBar

MozBar is a free SEO tool that makes it easy to identify canonical tags on any web page. Once installed, just click on the “Page Analytics” tab and select “General Attributes”. Here will display information about the website including ref = “canonical”.


Check Canonical tags with SEO tool MozBar

When to use Canonical URL

This section will list the cases of duplication between websites that lead to the need to set up Canonical URLs to improve SEO efficiency:

  • Duplicate pages differ only in subdomain www or http/https protocol: this is the most common case when the same website has up to 4 duplicate URLs as follows:
    • http://example.com
    • https://example.com
    • http://www.example.com
    • https://www.example.com
  • URLs with or without trailing slash: this is also one of the common use cases of canonical urls. The following 2 pages will be considered duplicate content:
    • http://example.com/home
    • http://example.com/home/
  • The URL version for PC and mobile: the two versions for the two devices will have exactly the same content, so it is also important to specify which is the Canonical URL. Eg:
    • https://baomoi.com/ (computer version)
    • https://m.baomoi.com/ (mobile version)
  • Duplicate page due to filter (filter): using filter to filter content often causes duplicate, easy to see in e-commerce websites. For example, searching for a lipstick by color, brand, and price filters will yield 3 different URLs even though the content is similar:
    • https://example.com/lipstick/s10020
    • https://example.com/lipstick/s10021
    • https://example.com/lipstick/s10023

The above points out the most common cases and the need to apply Canonical URLs to avoid being recognized by search engines as duplicates or having difficulty ranking on SERPs.

How to set Canonical URL?

Let’s say you have two versions of the same page, each with 100% identical content and both likely to rank on search engines. The only difference is that they belong to 2 separate sections of the site. So what is the URL that is allowed by search engines to show up in the SERPs?

This situation is quite common, especially in e-commerce sites where a product can have many different URLs. In this case, Canonical will come into play.

Set Canonical URL with rel=”canonical” tag in html

Using the rel=”canonical” tag in html is the simplest implementation to specify the root link. You just need to add a small code snippet in the section of any duplicate pages. Specifically follow these steps:

Step 1: Choose 1 of the duplicate pages as the canonical version: This is the URL you consider the most important, or you can prefer to choose a URL that has high traffic or is associated with many other pages.


Canonical URL is the most “canonical” page chosen to show on SERPs

Step 2: Add below code to duplicate pages. Then the duplicate URL will link to the Canonical URL in the section of the page as follows:

Replace “url-chuan” with the URL selected in the first step. Doing it this way is similar to “unifying” two pages into one from a search engine’s perspective.

Setting Canonical URLs in WordPress

To make it easier to imagine, let’s take a look at the following example: You have 2 articles belonging to 2 different key groups, let’s say:

  • Mua follow Instagram
  • Service to increase Instagram followers

After a while of posting, Google noticed that although users searched with two different keywords, they were directed to the same page of content. As a result, the keyword “buy instagram followers” was on the top with the article “Instagram follow-up service”. At this time, the post “Buy follow instagram” becomes a duplicate content bar. And now the Canonical tag will help solve the problem with how to do it on WordPress as follows:

  • Step 1: Log in to your WordPress account, select the duplicate post that needs to be put
  • Step 2: Scroll down to the bottom of the article, select Advanced.
  • Step 3: Copy the selected canonical URL, paste it into the Canonical URL section

Insert the selected canonical URL in the Canonical URL box

  • Step 4: Click Update to finish


Clearly understand What is Canonical URL?, the benefits it brings as well as knowing how to apply Canonical URL properly, you will be able to perform SEO optimization more effectively. Above are the shares of SEOVietNam on this topic, hope you have gained useful information for the SEO process.

Categorized as Tips

By Nguyen Manh Cuong

Nguyen Manh Cuong is the author and founder of the nguyendiep blog. With over 14 years of experience in Online Marketing, he now runs a number of successful websites, and occasionally shares his experience & knowledge on this blog.

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