Glossary
What is a canonical tag?
A canonical tag is a link element, rel="canonical", in a page's head that tells search engines which URL is the main version when the same or similar content is available at several URLs. Google treats it as a strong hint, alongside redirects, internal links and sitemaps, when choosing the canonical.
Syntax
<link rel="canonical" href="https://www.example.com/glossary/backlink/" />
Use absolute URLs and a self-referencing canonical on every indexable page.
When you need it
- The same page at several URLs: tracking parameters, sorting, print versions.
- http and https, www and non-www, with and without trailing slash.
- Syndicated content republished elsewhere.
How Google decides
Google considers redirects, canonical tags, internal links, sitemap URLs and whether the page is https, then picks one. If your signals disagree (canonical says one URL, internal links point to another), Google may choose differently from what you intended. Search Console's URL Inspection shows the "user-declared" and "Google-selected" canonicals.
Common mistakes
- Canonical pointing to a URL that redirects.
- Internal links using a different URL form than the canonical, such as no trailing slash.
- Canonicalising paginated pages to page 1.
- Using canonical instead of a redirect for moved pages.
Example
A site's canonicals use /glossary/backlink/ but its internal links use /glossary/backlink. Every internal link goes through a redirect, and Search Console lists the slashless URLs as "Page with redirect". Making links match the canonical clears it.
FAQ
Is a canonical tag a redirect?
No. Visitors stay on the page; only search engines get the hint.
Should every page have a canonical?
Yes, a self-referencing one on indexable pages is good practice.
Can Google ignore my canonical?
Yes, if other signals point elsewhere.