The canonical tag signals to search engines which URL should be considered the“original” version if several URLs have identical or similar content. This helps to avoid problems with duplicate content, improve the visibility of the page and consolidate link equity.
In this article, you will learn how canonicals work, how to implement them correctly and which best practices and common mistakes you should be aware of in order to optimize your website’s SEO performance.
What is the purpose of a canonical tag?
A canonical tag is an important HTML element that was specially developed for SEO. Its main purpose is to signal to crawlers which page is the original URL if several URLs contain identical or very similar content.
This helps to avoid duplicate content and optimize SEO performance.
Why is duplicate content problematic?
Google & Co. want to offer their users the most relevant and highest quality content. If a search engine finds several versions of the same page, it may have difficulty deciding which version should be displayed in the search results.
This can lead to a fragmentation of the ranking and reduce the visibility of the affected pages.
A common cause of duplicate content is the technical structure of a website where the same content is accessible under different URLs. This can happen through session IDs, tracking parameters or different sorting and filter options in online stores, for example.
Missing or incorrect redirects, for example if a page is accessible both via “www” and without “www” or via HTTP and HTTPS, often lead to duplicate content.
Another reason is the reuse of content on different pages to fill them with minimal effort or the copying of product descriptions from manufacturers. The catch is:
What does a canonical tag do?
A canonical tag tells search engines which URL should be considered the preferred version. This is done by adding a special HTML tag to the section of a page:
<link rel=”canonical” href=”https://www.example.com/preferred-page-url”>
This leads to:
- Avoiding duplicate content: By setting a canonical URL, you are telling the search engine that it should index and evaluate this URL, even if there are other pages with identical or similar content.
- Consolidation of link equity: If several pages with identical content exist and backlinks point to each of these pages, the link equity (the value conveyed by backlinks) is distributed across these pages. A canonical tag helps to concentrate the link equity on the preferred page.
- Clear prioritization: Search engines know exactly which page should be prioritized, which helps it to rank better.
How do I set a canonical tag?
Inserting a canonical URL is relatively simple and requires only a few steps. Here is a step-by-step guide:
- Identify the canonical URL: Determine which page version should rank preferentially.
- Add the canonical tag: Integrate the canonical tag into the <head> area of the HTML file of the respective page.
Let’s assume you have two URLs that have the same or similar content:
- https://www.example.com/page1
- https://www.example.com/page1?ref=123
To indicate that the first URL is the preferred version, add the following code to the section of both pages:
Step-by-step instructions
- Determine the main page: Select the URL that is to be displayed as the main page for users and the search engine.
- Open the HTML code of your page: Open the source code of your website. This can be done directly on your server or via a CMS (content management system). With WordPress, you will probably use a plugin such as Yoast or Rankmath.
- Insert the canonical tag: Place the canonical tag in the <head> area of the HTML code, directly after the <title> tag or the meta tags.
- Save and test: Save the changes and test the page to ensure that the canonical tag is implemented correctly.
Set canonical tags with Rank Math plugin
If you use the Rank Math SEO plugin on your website, you can easily define the canonical URL. To do this, edit a page/post and open the Rank Math functions on the right:
Then switch to the “Advanced” tab and you will find an input field at the bottom where you can specify the canonical URL:
Set canonical tags with Yoast SEO plugin
If you use Yoast, it’s just as easy. In edit mode, search for the Yoast settings and click on “Advanced”
You will then find an input field for the canonical URL:
Tools for checking
- Google Search Console: With this tool you can check whether Google recognizes your canonical tags correctly.
- Ahrefs, SemRush, ScreamingFrog
What is a canonical page?
A canonical page is your or your website’s preferred version for search engines to index and display in search results. It is the primary URL that you set to avoid duplicate content issues and ensure that SEO performance is focused on that specific URL.
Criteria for a canonical page:
- High-quality and relevant content: The canonical page should offer high-quality and relevant content.
- Search engine optimized: It should correctly implement all basic SEO practices such as title tags, meta descriptions and structured data.
- Backlinks: Ideally, most backlinks should point to the canonical page to maximize link equity.
Best practices in dealing with canonical tags
A canonical tag can be easily placed in the HTML code of your website. When using canonicals, you should pay attention to consistency and a clean URL structure, use self-referencing tags and also mark paginated pages to avoid duplicate content.
1. remain consistent
Make sure that the canonical tag is set consistently on all relevant pages. This helps crawlers to better understand the structure of your website and ensure that the right page is prioritized.
2. use self-referencing tags
The canonical page itself should also have a canonical tag that refers to itself. This helps to create clarity for the search engine.
3. use canonicals for pagination
You should also use canonical tags for paginated content (e.g. on a blog or product lists in an online store). Set a tag on each page of the pagination that refers to the main page.
Example of paginated blog pages:
<link rel=”canonical” href=”https://www.example.com/blog”>
4. avoid unnecessary parameters
If possible, avoid unnecessary URL parameters. Use the cleanest and simplest URL as the canonical link.
Do: <link rel=”canonical” href=”https://www.example.com/seo-tipps”>
Don’t: <link rel=”canonical” href=”https://www.example.com/seo-die-besten-tipps-fuer-anfaenger”>
5. regular monitoring
Regularly monitor the effectiveness of your canonical pages using tools such as Google Search Console. Make sure that no errors occur and adjust the tags if necessary.
Common errors
Missing or too many canonicals, incorrect linking or ignoring HTTPS can affect the SEO performance of your website. Make sure you avoid the following mistakes:
1. missing canonical tags
We can’t say it often enough: not setting canonical tags can lead to massive duplicate content problems and affect the SEO performance of your website. Make sure that all relevant pages have a canonical tag.
2. incorrect linking
Make sure that the canonical tag refers to the correct URL. A common mistake is linking to an incorrect or non-existent URL, which leads to confusion among crawlers.
3. too many canonical tags
Avoid setting multiple canonical tags on a page. Each page should only have a single canonical tag to send clear signals to the search engine.
4. dynamic URL parameters
If your website uses dynamic URL parameters, this can lead to many URL versions displaying the same content. In this case, you should set the canonical tag to point to the main or “cleanest” URL version to show the search engine the preferred version.
5. ignoring HTTPS
The canonical tag should refer to the HTTPS version of the page if your website has a secure connection (SSL). This prevents search engines from treating HTTP and HTTPS versions of the same page as duplicates.
Avoid duplicate content and maximize your SEO
Canonicals are used when the content of several pages on your website is similar or even identical. They are an indispensable tool in search engine optimization to avoid duplicate content and maximize the SEO performance of your website.
The tags are placed in the HTML code of the individual pages of your website. Implementation is simple if you follow or avoid our best practices and common mistakes.
By implementing canonical tags correctly and monitoring them regularly, search engines can index and evaluate the preferred page version correctly. This increases your visibility and leads to better rankings.