What is Canonical Tag in SEO

What is Canonical Tag in SEO

Using multiple sites that use the same content or a shopping website that uses slightly different content is very common. In such cases, it may be difficult for search engines to differentiate which is the master copy of all the similar-looking pages.

The search engine will select any random page and rank that on SERP, whether original or duplicate. In this case, you will lose a chance to rank your original page that contains all the vital information. To solve this issue, you can use canonical tags on your page. It helps search engines differentiate the original and duplicate copies of the web page.

Let's learn about canonical tags, their benefits, how to add them to your website, and the best SEO practices for using them.

What is Canonical Tag?

The 'Canonical Tag' or 'rel canonical' is one type of tag that indicates to the search engines that the URL of the page is the original version. It is used in the head section of your HTML page or HTTP header.

Canonical Tags help you in ranking the original page in search results. It prevents search engines from ranking and indexing duplicate, near-duplicate, and similar page versions.

Importance of Canonical Tags in SEO

Google prefers to crawl and index one page instead of all the pages with the same content. If you're using duplicate content on various website pages, Google should know which page is original. Otherwise, its crawlers will have multiple versions of the same page, and you may miss the chance to rank your original content, which can affect your SEO strategies and crawl budget. 

A canonical tag is essential for SEO as it helps you control duplicate content. Specifying the canonical tag for that particular page will indicate to the crawlers of search engines that this is the original page you want to index. Google will only rank that page in SERPs.

How to Implement Canonical Tags?

You can specify the canonical tags in your page using two methods: in a web page's HTML or HTTP headers. You can do it manually or automatically through available tools. For example, if you use a content management system like WordPress, you can use available SEO plugins such as Yoast SEO, SEO Framework, and All in One SEO. However, remember to use the canonical tag at one place on the page; otherwise, Google will ignore all of them.

  • HTML Tag: This is the most common method of adding canonical tags to your HTML page. If you want to implement it for other files, you can use HTTP. You can add the following looking code in the <head> section of your webpage,

<link rel=”canonical” href=https://www.example.com>

  • HTTP Header: You can specify the canonical version of your URL in the HTTP header. For non-HTML documents like PDFs, use HTTP instead of HTTPS. Access your website server and use the following code in the HTTP header.

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

This method requires a person with technical skills as it's more error-prone and difficult to implement than canonical tags in HTML pages.

Canonical Tag Best Practices

Canonical tags can effectively boost your web page's performance in search engine result pages. You can follow the below-mentioned best practices while implementing canonical tags.

Use the Correct Domain Version

Websites use unsecured or secured (SSL) protocols to secure their page from unauthorized access. Websites with unsecured protocol use 'HTTP' in its URL, while websites with SSL protocol use 'HTTPS' in its URL. Use the correct domain version in your canonical tags if your website has moved from non-SSL to SSL. Otherwise, it will confuse Google search algorithms, and you will not get the expected results.

Use Absolute URLs

Always use a complete URL in your canonical tag. Your URL should have the HTTPS://, WWW, domain name, and .com. The URL added after this part is the 'relative URL,' which is not recognized by Google when it reads your canonical tag. If you use only relative URLs, Google will ignore your canonical tag.

Use Self-Referencing Canonical Tags

It's not mandatory but recommended. Use a self-referencing tag that points towards itself. For example, if the URL is https://SEOtechniques.com/query-page, then use the self-referencing canonical tag as:

<link rel=”canonical” href=” https://SEOtechniques.com/query-page” />

Modern content management systems automatically do self-referencing. In custom content management systems, you have to do it manually.

Avoid Sending Mixed Signals Using Canonical Chains

Use a straightforward approach while writing canonical tags. Don't use canonical chains, as it confuses Google to interpret the tags. For example, if your page A is pointing to page B, don't point page B to page A again. It will create an ambiguous canonical situation, and Google will ignore your tag or misinterpret it, resulting in unexpected results.

Use Lowercase URLs and Only One Canonical Tag Per Page

URLs with uppercase and lowercase letters are considered different by Google. Therefore, force lowercase URLs on your server and use them in canonical tags. Apart from that, only use a single canonical tag per page. If your page contains more than one canonical tag, Google will ignore them.

Add Canonical Tags to your Home Page

Duplicating any homepage is common and can be done in many ways. Various other sites can easily duplicate your website content and present the same content differently. If this happens, the search engines will need clarification in deciding which page is original and deserves to be ranked. Adding a relevant canonical tag on your homepage will help the search engine differentiate a master copy and a duplicate copy.

Make Use of Near-Duplicates with Care

You can also use canonical tags for near-duplicate pages, but you must implement them carefully. For example, if you are a shopping site whose product content page only slightly differs in price, location, and some product description, you can use a canonical tag. However, search engines may only rank that page and not other product pages.


Canonical tags are essential if you use duplicate or near-duplicate content on your website. Using canonical tags is the best for your SEO, as it tells Google that you want this specific page to rank and index. It will make the process of crawling easier and will also save your crawl budget.

However, canonical tags are difficult to implement when you want custom tags for your URLs, as there are multiple ways to implement them. So, getting some technical knowledge before implementing them for your pages is better. If you need to improve the technical aspects of SEO, we are here to help. We provide the best SEO services that help you grow your business. Call us to learn more about our services.

Amit Kumar Khare

Author: Amit Kumar Khare

Amit is a tech enthusiast and loves writing about it. He is a senior developer with good hands-on experience in digital marketing.

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