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A Beginner’s Guide to Canonicalization in SEO and Its Implementation

Diana Aghumyan

Table of Contents

What’s the biggest fear in SEO? You may say, not being visible on the engines. Yet, the biggest, scariest outcome for many experts is getting penalized. Since ranking can be fixed, however, penalization by Google is a tougher play. In this scenario, you should identify all existing issues and work towards improving the optimization aspects.

Canonization in SEO aims at reducing the risk of penalisation. As per the statistics, 60% of the Internet is duplicate content. Canonicalization aims to eliminate duplicate content and ensure better indexing by Google spiders. Choosing the best URL or preferred webpage URL out of multiple versions of the same page accessible through different URLs is referred to as canonicalization in SEO. Simply put, canonicalization in SEO deals with resolving URL variations and combining them into a single, canonical URL. 

Why is Canonicalization in SEO Important?

Imagine a scenario where you want the page with the keyword “legal documents” to rank; however, you mistakenly have two URLs on your webpage where “legal documents” is the keyword. When a searcher enters the key phrase in the Google search bar, the indexing spiders crawl and find those two matching URL tags. Your website has duplicate content, which you know engines dislike. 

If this happens regularly, the page gets noticed and penalized. 

Here you behold the importance of canonicalization in SEO to avoid the issue of duplicates happening. Search engines may index multiple webpage versions without proper canonicalization, leading to duplicate content issues and diluting page authority. The ultimate result is harming the website’s search engine rankings. 

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Proper canonicalization ensures that search engines understand the relationship between different webpage versions and assign appropriate ranking signals. The important and beneficial aspects of canonicalization for SEO include the following:

  • Avoiding duplicate content penalties from SEs
  • Consolidating link equity and improving PA
  • Reducing crawl and indexation issues for SEs
  • Improving UX by directing users to the preferred version of a webpage
  • Facilitating ranking important pages by avoiding competition between versions of the same page.

What are the Types of Canonicalization in SEO?

Various types of canonicalization can be used depending on the kind of website and its content. Understanding these different types of canonicalization is crucial to properly implementing a canonicalization strategy that fits your website’s needs. Here are some of the common sorts of canonicalization in SEO. Website owners should be aware of and use those to ensure search engines index the preferred version of their website.

Domain Canonicalization

Domain canonicalization is designating the authoritative version of a website’s domain name. A website proprietor may employ domain canonicalization to specify the preferred version of their website’s URL, with or without the “www” prefix.

HTTP vs. HTTPS Canonicalization

HTTP and HTTPS are two different protocols for website communication. HTTP is Hypertext Transfer Protocol abbreviated while HTTPS stands for Hypertext Transfer Protocol Secure. In HTTP vs. HTTPS canonicalization, website owners choose which version of their website they want search engines to index.

WWW vs. non-WWW Canonicalization

This type of canonicalization involves choosing the preferred version of a website’s URL. For instance, a website owner may canonicalize their URL to include or exclude the “www” prefix.

Parameter Canonicalization

Parameter canonicalization is used when a website has dynamic content, such as product filters or sort options. With parameter canonicalization, website owners choose the canonical version of the page and specify which parameters to ignore.

Content Canonicalization

Content canonicalization is used when a website has identical or similar content on multiple pages. With content canonicalization, website owners choose the preferred version of the content and specify which pages to canonicalize to that version.

Cross-Domain Canonicalization

Cross-domain canonicalization is used when a website has content that appears on multiple domains. With cross-domain canonicalization, website owners specify the preferred domain for search engines to index.

How to Implement Canonical Tags

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To begin with, let’s understand what’s a canonical tag.

Canonical tags, also known as rel= “canonical” tags, are HTML attributes that indicate for search engines which version of a webpage is authoritative. Canonical tags are essential for resolving duplicate content issues and ensuring that search engines index the preferred version of a webpage.

To implement canonical tags in HTML code, website owners must first identify the authoritative version of their webpage. This involves determining the preferred URL version, the preferred domain name (with or without the “www” prefix), and the preferred protocol (HTTP or HTTPS). Once the authoritative version has been identified, website owners can insert the canonical tag in the HTML code of their web pages.

To insert a canonical tag, website owners must include the rel= “canonical” attribute in the HTML code’s head section and specify the URL of the authoritative version of the webpage. Ensuring that the canonical tag is correctly implemented and appears on every webpage that requires canonicalization is essential.

To ensure effective implementation of canonical tags, website owners should follow best practices, such as avoiding self-referencing canonical tags, using absolute URLs, avoiding redirect chains, and avoiding canonicalizing non-duplicate content. It is also crucial to regularly monitor the effectiveness of canonical tags and adjust the strategy as necessary to ensure optimal results.

Common Mistakes for Canonicalization in SEO to Avoid

Canonicalization holds many benefits for SEO; it is a critical and important component. However, it’s not without its pitfalls. Many aspects should be accounted for to direct it to the right path. Below are some of the common mistakes which, along with common SEO mistakes, should be avoided when implementing canonicalization on your website:

Choosing the wrong canonical URL

This can occur when a website owner designates a URL as the authoritative version that is not intended. For instance, selecting a URL with parameters instead of a clean URL can lead to indexing issues and negative impacts on search engine rankings.

Targeting the wrong pages 

This happens when website owners mistakenly designate a page as the authoritative version, even though it is not the most relevant or essential page. To avoid this mistake, website owners should identify the most relevant page and use it as the canonical URL.

Using incorrect canonical tags 

This can occur when website owners use the wrong syntax or improperly implement canonical tags, leading to confusion for search engines and negative impacts on website visibility in search engine rankings.

Canonicalizing pages with different content

While canonicalization can effectively resolve duplicate content issues, it should not be used to address pages with different content. In such cases, website owners should consider using other SEO techniques to improve website visibility, such as optimizing page titles and meta descriptions.

Insights for canonical content in SEO

To summarize, canonicalization is a crucial aspect of SEO. It helps reduce the risk of penalization, improve website indexing, consolidate link equity, reduce crawl and indexation issues, and enhance user experience. 

There are different types of canonicalization, including domain, HTTP vs. HTTPS, WWW vs. non-WWW, parameter, content, and cross-domain canonicalization. Implementing canonical tags is essential to ensure effective canonicalization. Website owners must follow best practices and avoid common mistakes such as choosing incorrect canonical URLs, using self-referencing canonical tags, and canonicalizing non-duplicate content. Website owners can ensure optimal results and improve their search engine rankings by properly implementing canonicalization.


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