Canonical Tags: The Basic Guide to Canonical URLs | Varn


13 December 2023

Canonical Tags: The Basic Guide to Canonical URLs

In popular culture, the word ‘Canon’ signifies a body of work that is the official narrative. Anything outside of that may look like and use inspiration from the original, but it cannot be called the original. Similarly, websites use canonical URLs to signify to search engines which URL is the principal version and should be shown in search results. 

For example:

Canonical URL: 

Alternative URL: 

Both the alternative URL and the canonical URL will have the canonical tag in the page’s source code, confirming that the canonical URL is the primary version of the page. Here we will be talking about canonical tags and their role in good SEO practice for your website. 

What is a Canonical Tag? 

A canonical tag, which is also known as rel=”canonical” tag, is a piece of HTML code that allows you to outline the principal canonical URL for search engines to pick up. Each page should have a canonical tag, especially the principal URL itself. Self-referencing canonicals are important to make it clear to search engines that ‘this’ page is the principal and should be shown in search results. 

Why Use a Canonical Tag for Your Website? 

Using canonical tags is good SEO practice and will make crawling your site easier and smoother for search engines. Canonical tags are essential on websites with high potential for duplicate or near duplicate content such as eCommerce websites, sites with multiple language options and sites with listing pages that have filters or sorting options. 

Not only can duplicate content be penalised by search engines such as Google, but it can also cause keyword cannibalisation. This occurs when multiple pages are competing for the same keywords, which has a negative effect overall on the site’s rankings. 

How and Where to Use Canonical Tags

Canonical tags should be added as a line of HTML code in the <head> section of the page and look like this:

<link rel=”canonical” href=”” />

However, your content management system (CMS) or CMS plugin may have a section for you to add the canonical URL separately. 

Problems to Look Out for With Canonical Tags

There can be many issues when it comes to canonical URLs and tags. Although, with careful planning and implementation, they can be avoided. These issues include blocking the canonicalised URL in the robots.txt file, preventing crawling from search engines, as well as setting canonicalised URLs to noindex, which allows crawling but doesn’t allow indexing. 

Another mistake when implementing canonical tags is setting the canonical URL of all pagination pages to that of the root page. You may think that by searching for “women’s dresses”, a relevant website will want each paginated page in the women’s dress category to point towards page 1. 

Google, for example, uses other methods such as internal linking, page sequencing, sitemaps and more to recognise pages accordingly, and we think you’d agree with us it’s doing a pretty good job. 

It’s noteworthy that Google no longer uses ‘prev/next’ tags. However, other search engines still do. 

Using Hreflang Tags Alongside Canonical Tags

Hreflang tags and canonical tags are both important in helping search engines discern between possible duplicate content, such as the same pages in different languages. Hreflang tags are more specific, using language and region as instructions, whereas canonical tags tell search engines the principal page to show out of similar pages.

When using hreflang tags alongside canonical tags it can be confusing, for you and search engines. Duplicate pages should canonicalise back to the primary page within the relevant language. For example, if your site is based in the UK, but has a German language version for users in Germany, it should look something like this:

<link rel=”alternate” href=” hreflang=”de-de”/>

<link rel=”alternate” href=” hreflang=”en-us”/>

<link rel=”canonical” href=”/>

The above code would be used on both the primary version of the page and the duplicate version. Even though the principal site is based in the UK and is written in English, the canonical URL for German users in Germany is the German version of the site.

Canonical Tags Vs 301 Redirects

If your page is canonically pointing to another page, it may seem logical to implement 301 redirects to the canonical page, right? It’s a bit more complicated than that. While it’s true that redirects are directives, forcing the linked-to page to load instead, canonicals are more of a suggestion, which search engines could choose to ignore. 

Both canonical tags and 301 redirects have their uses in websites, and each has its appropriate place. There are instances where a 301 redirect should be used, such as when you have multiple similar pages, except only one is relevant. The no longer relevant pages should be redirected to the up-to-date page. For example, pages removed from your site, pages that have moved URL, and listings no longer valid.

Get in Touch for a Comprehensive SEO Audit 

If you want to know how canonical tags are implemented on your website and their effect on your site’s ranking power, drop us a message today. The SEO experts here at Varn will get back to you in no time. 

Article by: Alexis, Technical SEO Executive More articles by Alexis

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