SEO
Canonical URL
The preferred version of a page when duplicates exist.
A canonical URL is the version of a page you tell search engines is the "real" one when multiple URLs serve the same or similar content. Specified with `<link rel="canonical" href="...">` in the page head.
Common duplicate scenarios: with/without trailing slash, with/without www, HTTP vs HTTPS, sorted/filtered product listings, AMP versions, and syndicated articles. Without a canonical, Google picks one itself — usually the wrong one.
Self-canonicals (a page declaring itself the canonical) are normal and recommended. Cross-canonicals point to a different URL when content is genuinely duplicated. Setting one wrong can deindex your page.
Related terms
Postwyse solves this with