What is a Canonical Tag?
Canonical tags exist to resolve issues related to duplicate or similar content existing on multiple URLs.
You may need them when the same content is accessible via different URLs. It’s rather common in e-commerce platforms where multiple paths can lead to the same product page or in content management systems that generate printable versions of pages.
Duplicate content can dilute link equity and impact search rankings, as search engines just don’t know which version of the content to index or rank.
The canonical tag should be placed in the <head> of the HTML of the webpage and can be used to point search engines to the URL you consider to be the most authoritative (canonical) version.
It ensures that search engines index the preferred page, and any link signals and ranking power are attributed to this designated URL rather than spread across multiple similar pages.
How to Use Canonical Tags
To use canonical tags effectively:
- Identify duplicate content, look for URLs with identical or similar content on your site;
- Choose the canonical version (the version of the content you want search engines to index and rank);
- Add the <link rel=”canonical” href=”http://www.example.com/preferred-url.html”> tag to the <head> section of the duplicate pages’ HTML;
Always use the absolute path (the whole URL) in your canonical tags to avoid confusion. Keep in mind that the target of your canonical tag should be accessible and match the content of the duplicates.
Even on the canonical page, you may need to include a self-referential canonical tag to reinforce the canonical designation.