Canonical URL
The authoritative URL for a page when duplicate or near-duplicate versions exist.
A canonical URL is declared via a rel="canonical" link tag and tells search engines which version of a page should be treated as the primary. Duplicates point to the canonical to consolidate ranking signals.
Context
Common uses: pagination (page 2 canonicals to page 1, or better, self-canonicals), UTM-tagged URLs (canonical to clean URL), product variants (variant canonicals to primary SKU), and near-duplicate content (localized variants canonical to primary).
A canonical URL should return 200, be indexable, and be the URL you want ranking. If canonical points to a 404 or a noindex page, the canonical signal is discarded and you may end up with duplicate content issues.
A product page at /shoes/running/blue-size-10 with color and size variants typically canonicals to /shoes/running — the parent product page — so all variant signals consolidate on one URL.
Canonical is a hint, not a directive. Google can ignore canonical if the signals are contradictory — for example, if the canonical URL differs from the sitemap URL differs from the internal linking pattern, Google picks its own.
Related terms
Services that apply this
More SEO terms
CTR (Click-Through Rate)
The percentage of people who clicked after seeing your link, ad, or snippet.
SERP (Search Engine Results Page)
The page Google shows after a search — far more than just ten blue links.
LCP (Largest Contentful Paint)
How fast the main content becomes visible on a page.
CLS (Cumulative Layout Shift)
How much the page jumps around during load.