Have you ever wondered how search engines know which version of a webpage is the original? Or how they handle multiple URLs pointing to the same content?
The answer lies in canonical URLs and tags.
These elements help search engines understand your site structure and prioritize the right pages.
In this beginner’s guide, we’ll break down what canonical URLs are, how they differ from canonical tags, and how to use them effectively.
In This Article
What Is a Canonical URL?
A canonical URL is the preferred version of a web page. It’s considered the “master” of a piece of content.
When search engines encounter multiple URLs pointing to the same content, they use the canonical URL to determine which version to index and rank.
What Are Canonical Tags?
Canonical tags are an HTML element that communicates the canonical URL to search engines.
Here’s what it looks like in HTML code:
<link rel="canonical" href="https://example.com/canonical-url/" />While the canonical URL is the target destination, the canonical tag is the tool to signal it to search engines.
When You Should Use Canonical Tags
Knowing when to use canonical tags is essential for keeping your website healthy and organized.
Let’s explore the main situations where using canonical tags is beneficial:
1. URL Variants
Imagine a web page as a shop with multiple doors for entry.
Each door leads to the same store, but the entrance is technically different.
Sometimes, users can reach the same page of a website through different “doors” (URLs.)
For example, one URL might start with “www” and another without.
While they both lead to the same web page, search engines might consider them separate “stores.”
This can confuse them and hurt your SEO rankings.
Here’s where canonical tags come in.
Canonical tags act like signs pointing search engines to the main entrance you want them to use.
They can aid with URL variations, such as:
- HTTP vs HTTPS: Secure vs. non-secure versions of your site.
- Uppercase vs. Lowercase: “Example.com” is the same as “EXAMPLE.COM”.
- Trailing Slash vs. Non-Trailing Slash: Both lead to the same page, but you want to pick a preferred version.
By using canonical tags, you ensure search engines recognize the definitive URL for your content.
2. Duplicate Content
Large shops often display the same items in different sections.
Similarly, your website might have the same product accessible through different categories or tags. (This is often the case for eCommerce sites whose various filters or navigations can affect the final URL of a product.)
This situation creates an unintentional issue of duplicate content.
A canonical tag on each variant URL helps search engines determine the most important version.
This ensures your duplicate pages aren’t competing against themselves and that the main page is shown in search results.
3. Syndicated Content
Imagine opening a second location for your store. Even though you may physically work out of the first location, you still want customers to know you’re the owner of the second shop, right?
A canonical tag in the “second shop” (syndicated content) pointing back to your original store (website) does just that.
Syndicated content is when the same piece of content is published on multiple websites.
By using a canonical tag on the syndicated content, you tell search engines that you’re the original owner.
This helps search engines attribute the SEO value to your page.
4. Site Migrations
In this scenario, imagine you’re moving your store to a new location.
You want to communicate all the new store’s details but keep your customers.
Canonical tags are essential when migrating your website to a new domain. They tell search engines which new URLs have replaced the ones, preserving your existing customer base (rankings and authority).
Without canonicals during migrations, your SEO could suffer as search engines struggle to find your new location.
By including them, you ensure search engines preserve your SEO and index and rank the correct versions of your content.
5. Paginated Pages
For this last scenario, imagine a product catalog. It consists of a long list divided into multiple pages.
While each page is unique (URL), they all contribute to the same product catalog (your content.)
A canonical tag on paginated pages tells search engines to treat the series as a whole and index the first page only.
It’s like saying, “Hey, instead of serving the fifth page of my product catalog, give my customers the whole book.” They can still browse the individual pages and products, but find this information through the main book.
This strategy avoids those individual pages getting ranked separately and competing against one another.
The first page should have a self-referencing canonical tag pointing to itself. This reinforces its status as the primary page for the paginated series. (We’ll get into this in more detail in our next section.)
Subsequent pages should link back to the first page using a canonical tag. This ensures that search engines understand the hierarchical relationship and attribute the value to the main page.
What About Self-Referencing Canonicals?
Self-referencing canonical tags are canonicals that point back to themselves.
Here’s an example of one taken using the All in One SEO Analyzer Chrome extension:
While it might seem unnecessary, self-referencing canonical tags can be beneficial for clarity purposes.
There’s no room for search engines to misinterpret which page you want them to rank and index.
Google Search Advocate, John Mueller, also recommends using self-referencing canonical for this exact reason.
How to Specify a Canonical URL
Various methods can be used to specify a canonical URL.
Here are a few recommended approaches:
Google Search Console Guide
Google provides an in-depth guide for specifying canonicals on your web pages.
It demonstrates three methods using:
- Rel=”canonical” link annotations (see image below)
- Sitemaps
- Redirects
This Semrush tutorial also shows you how to set canonical tags in Magento 1 and 2, Shopify, and Wix. It can be a helpful resource when setting canonicals to specific platforms.
SEO Plugin [WordPress]
For WordPress users, SEO plugins can simplify the canonicalization process.
Take All in One SEO (AIOSEO), for example.
After navigating to the Advanced settings, it’s as easy as entering the canonical URL into the field.
AIOSEO will update your preferences upon saving.
This method is great for website owners unfamiliar with HTML code or prefer a more user-friendly method for managing their website’s canonicals.
Final Thoughts
By understanding and implementing canonical URLs, you can significantly improve your website’s SEO.
These HTML elements help search engines recognize the most important versions of your content.
They also prevent duplicate content issues and can enhance your Google rankings.
For further reading, explore these recommended articles:
- Negative SEO: What It Is & How to Protect Your Website
- 9 SEO Secrets to Unlock Higher Traffic & Revenue
- Keyword Research Trends You Need to Know in 2025
- How to Create Scannable Content in 5 Easy Steps
