Everything you need to know about canonical tags (and why they matter)

Think of canonical tags as the "boss" of your webpage content. When search engines like Google come across several pages on your website that are similar or identical (which happens more often than you might think), it can get a little confused. It doesn’t know which page to prioritise or show in search results. That’s where the canonical tag steps in. It’s a little snippet of HTML code that says, "Hey, this is the main page. Use this one!"

For example, you might have a page about a specific product that appears in different categories or has different filters (like colour or size options). Canonical tags tell Google which version is the one to focus on and rank.

Why should you care about canonical tags?

When Google sees multiple versions of the same content on your site, it can hurt your SEO (search engine optimisation), meaning your site’s ability to rank well in search results might take a hit because it isn’t sure which page to prioritise. Worse yet, sometimes none of them get prioritised!

But by using canonical tags, you make sure Google knows which page is the most important, meaning that page has a better chance of showing up in search results. Plus, it stops Google from splitting the ranking power between multiple versions of the same page.

Another big reason to use canonical tags is that they help prevent something called “duplicate content” issues. Duplicate content doesn’t just confuse Google; it can confuse your visitors too. Imagine going to a website and seeing two or three almost identical pages. Which one are you supposed to click on? Canonical tags tidy all that up.

When should you use canonical tags?

There are a few common situations where you’d definitely want to use canonical tags. For instance, if you have both mobile and desktop versions of your website, you can use canonical tags to tell Google which version you want to be the priority in search results. Same goes for secure (HTTPS) and non-secure (HTTP) versions of your site—canonical tags help ensure Google focuses on the secure version, which is better for your ranking.

Another example is if you run an online store. Let’s say you sell t-shirts, and you have one page for "red t-shirts" and another for "blue t-shirts," but they’re otherwise identical. A canonical tag helps Google know that the “red t-shirt” page is the one you want to prioritise in search results, without losing the traffic for the other versions.

It’s also useful if you’re sharing your content across multiple sites. You might have the same article published in several places, but you want the original on your site to get the SEO credit. The canonical tag points back to the original, ensuring it’s the one that ranks.

How do you actually add canonical tags?

Adding canonical tags to your website isn’t too difficult, and most platforms have made it fairly straightforward. If you’re using a content management system like WordPress or Shopify, you don’t need to know how to code. In WordPress, for example, an SEO plugin like Yoast SEO will automatically add canonical tags for you. Same with Shopify—Shopify automatically includes them on your product pages. If you want to tweak or add them manually, you’ll just need to pop into your site’s settings and add a simple line of code to the header of the page.

The code itself looks like this:

<link rel="canonical" href="https://example.com/sample-page/">

That’s it!

A few things to keep in mind

Now, while canonical tags are pretty easy to use, there are some best practices that can help you avoid headaches later. For starters, even if a page isn’t duplicated elsewhere, it’s still a good idea to use a self-referencing canonical tag. That just means you’re telling Google, “this page is the one to rank,” even if it’s the only version.

You also want to be careful about using canonical tags on pages that aren’t identical. Let’s say you have a product page with very slight differences, like one page for red shirts and another for blue. Those are fine to canonicalise, but if the pages are too different, Google might ignore your canonical tag altogether.

Something else to keep in mind—try not to mix signals. If you’re using a canonical tag, don’t also set up a redirect or add a "noindex" tag (which tells Google not to index the page). Those kinds of mixed messages can confuse Google and cause problems for your ranking.

Why canonical tags are good for your site’s health

Canonical tags are like giving your website a much-needed tune-up. They help Google understand your site better, make sure the right pages are showing up in search results, and prevent any unnecessary confusion. If you’ve got a site with lots of similar or identical pages (like an online store, blog, or multi-language site), canonical tags are a must.

Whether you’re just getting started with SEO or you’ve been working on it for a while, it’s important you don’t overlook the power of these tiny but mighty tags. They’re easy to implement, and they can make a big difference in how your site ranks and how users experience your content.

In the world of SEO, sometimes the smallest tweaks — like adding a canonical tag — can have the biggest impact.