Categories: SEO

What is Canonical URL? Complete Guide on URL Canonicalization

Canonical URL is an important term that every blogger should be aware of. Even if you have heard or not, you should know what role Canonical URL plays in the optimization of a website. I have referred to it multiple times in my previous articles. While doing SEO, we need to check both On Page SEO and Off Page SEO. But if you are not doing your On-Page SEO properly, you will not get good results, no matter if you are performing Off Page SEO well. So today, I thought to write an article on URL Canonicalization (Canonical URL) which is a part of On-Page SEO. This is going to a long article (Sorry for that :P). I am breaking it down in following:

  1. What Is Canonicalization or Canonical URL?:
  2. How To Do URL Canonicalization?
  3. Why Should You Care About Canonical URL or URL Canonicalization?
  4. Parameter Handling For Dynamic Parameters
  5. Should A Page Have A Self-Referencing Canonical URL?
  6. Few More Tips On URL Canonicalization

    1) What is Canonical URL?

To give canonical URL definition, a canonical URL is an authoritatively correct URL for a resource. Canonicalization is the process of choosing the best URL when there are several options. Are you confused? Let me explain this. Say following are the URLs to access the homepage of my site –

  • www.CatchUpdates.com
  • CatchUpdates.com
  • www.catchupdates.com/index.html
  • catchupdates.com/index.html

Above are the canonical URL examples for my blog. Although these are URLs pointing to my home page, technically speaking, all of these URLs are different. A web server sees these four unique URLs as four unique pages. Thus, a web server can return completely different content for all the URLs mentioned above. Since different content doesn’t exist on each of these variation URLs, and if URL Canonicalization is not done, Search engines view it as duplicate content (duplicates) and which can cause so many issues and result in lower website rank. To make sure the search engines are indexing the correct page, you need to select which variation of the URL you want to set as a canonical URL or canonicalized URL.

Once you have picked any version of the URL, say canonical URL, stick to it. A canonical URL is the one that you want visitors to see.

2) How To Do URL Canonicalization?

Before proceeding further, I hope you are now clear about what exactly the canonical URL or URL Canonicalization is. Now, we will see how to create a canonical URL. This is a very small task. We just need to use a canonical tag to apply Canonicalization. Your website might have been returning the same content in both www and non-www versions. In this case, you can apply the canonical tags (rel=”canonical”) to indicate that the second URL is a Canonical URL of the first one.

URL Canonicalization Tag

<link rel=”canonical” href=”http://www.CatchUpdates.com”>

Make sure you’ve specified the Canonical URL tag in your HTML header. Canonical tag should be placed inside the <head> tag – <head> </head> as shown below:

 <html>
<head>
<link rel=”canonical” href=”http://www.CatchUpdates.com/” >
</head>
<body> </body>

</html>

Make sure that every single variation of the URL is redirected to the canonical by way of a 301 Redirect. A server-side 301 redirect is the best way to ensure that users and search engines are directed to the correct page. The 301 status code means that a page has permanently moved to a new location.

 The easiest way to avoid this is to let the Search engines and the users know which is your “preferred URL” i.e. canonical URL. Tell Google which version of your site’s URL you prefer for your domain. Read Set your preferred domain for details.

3) Why Should You Care About Canonical URL or URL Canonicalization?

Now the next question is why you should care about Canonical URL or URL Canonicalization. The problem is with search engine bots. They cannot decide which version of the URL they should add in their index. If you have two or more pages resulting in the same content, the bots will assume one is a duplicate copy of the other. The worst part is, it can even get your website penalized. To avoid this, you can use rel=”canonical” tags to let the search engines know that which is the original and which one is a copy of it. This can save you from duplicate content penalties.

4) Parameter Handling For Dynamic Parameters

You may need to tell Google about any parameters you would like ignored. Ignoring certain parameters can reduce the duplicate content in Google’s index which makes your site more crawlable. For example, if you specify that the parameter category or sessionid should be ignored. Google will consider https://www.abc.com/Men/clothing.php?sessionid=273749 to be the same as https://www.abc.com/Men/clothing.php.

When this happens, site owners suffer rankings, and traffic losses and engines suffer lowered relevancy. So to avoid this, we need to use Canonical URL tag whenever any of the following scenarios arise:

You can read more about Parameter Handling here.

5) Should A Page Have A Self-Referencing Canonical URL?

This might look weird to you. As per Yoast, it is good to have canonical link element on every page. The reason being the most of CMS allow URL parameters without changing the content. So these would show the same content:

  • http://example.com/wordpress/seo-plugin/
  • http://example.com/wordpress/seo-plugin/?isnt=it-awesome
  • http://example.com/wordpress/seo-plugin/?cmpgn=twitter
  • http://example.com/wordpress/seo-plugin/?cmpgn=facebook

You should have a self-referencing canonical on the page that points to the cleanest version of the URL. So adding a self-referencing canonical to URLs across your site is a good “defensive” SEO move. And fortunately, WordPress SEO By Yoast plugin does this for you.

6) Few More Tips on URL Canonicalization

  • Do not canonicalize a paginated archive to page 1. Don’t add a rel=canonical on page 2 and further, search engines will actually not index the links on those deeper archive pages anymore.
  • Do not use robots.txt file for canonicalization purposes.
  • Lots of sites use protocol-relative links, meaning they leave the HTTP / https bit from their URLs. Don’t do this for your canonicals. Show your preference.
  • Do not use the URL removal tool for canonicalization: it removes all versions of a URL from search.
  • Do not specify different URLs as canonical for the same page (e.g. one URL in a sitemap and a different URL for that same page using rel=”canonical”).
  • Prefer HTTPS over HTTP for canonical URLs

Although our systems prefer HTTPS pages over HTTP pages by default, you can ensure this behavior by taking any of the following actions:

  • Add 301 or 302 redirects from the HTTP page to the HTTPS page.
  • Add a rel=”canonical” link from the HTTP page to the HTTPS page. (i.e. rel=canonical)

That’s all in this article. Keep in mind that canonicalization is a delicate process. Make sure you perform URL Canonicalization properly. If you have more questions, concerns, or experiences to share about the new URL Canonicalization tag, please do so in the comments.

Mohit Arora

Hi, I am Mohit Arora, a passionate blogger and addicted reader. You can check my another blog TutorialsJar where I share programming tutorials. You can connect with me on Instagram Or Quora And Linkedin as well. Subscribe to CatchUpdates feed via RSS

View Comments

  • Yes, really useful info and good useful update. i can easily grab your blog post. Thanks for that...

  • useful update. i can easily grab your descriptions unless other seo blog they would made complected explanation but here every thing is clearly explained and informative resource for every seo beginners thanks a lot.

  • This is nice Mohit, I was wondering why every page should have this tag but looking into your post I am clear now and now I think its good practice to have this tag on every page so that all factors can be transferred to main page.

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