A canonical tag tells search engines which URL is the main version of a page when similar versions exist. It looks like this in the page’s head:
<link rel="canonical" href="https://www.example.com/products/cotton-bedsheet/">
When you need it
- Product pages reachable through several category paths.
- URLs with tracking or filter parameters, such as ?utm_source= or ?color=blue.
- Content syndicated on other sites with your permission.
Self-referencing canonicals
It is good practice for each page to have a canonical tag pointing to itself. Many CMSs and SEO plugins do this automatically.
Canonical vs redirect
| Canonical | 301 redirect | |
|---|---|---|
| Visitor sees | The page they opened | Sent to the new URL |
| Use when | Both versions need to exist | The old version should disappear |
| Strength | A strong hint to Google | A clear instruction |
Common mistakes
- All pages pointing their canonical to the home page.
- Canonical pointing to a page that redirects or returns an error.
- Using http in the canonical on an https site.
Check it
The URL Inspection tool in Search Console shows which canonical Google selected. Break down URLs with our URL parser, and generate head tags with our meta tag generator.
Want the full picture? This article is part of SEO: the complete guide, our in-depth guide with everything in one place.
