Resources/Glossary/Canonical Tag

SEO Glossary

Canonical Tag

Tells search engines which URL is the preferred version.

A canonical tag (rel="canonical") is an HTML element that tells search engines which version of a URL is the "authoritative" or "preferred" version. It is used to prevent duplicate content from diluting ranking signals across multiple similar URLs.

Common scenarios requiring canonicalization: paginated content (page 1 vs page 2), parameter-based URLs (product pages with sort/filter parameters), HTTP vs HTTPS versions, www vs non-www, and content syndicated to multiple domains.

Canonical tags are a hint, not a directive. Google may override them if it determines the tag is incorrect or if another signal (like a redirect) contradicts it. Canonical errors are one of the most common findings in technical SEO audits.

Example

Your product page is accessible at /products/widget/, /products/widget?color=red, and /products/widget?ref=homepage. A canonical pointing all variants to /products/widget/ consolidates their signals.

Apply this in practice

Definitions are step one.

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