Canonical URL
Also known as: rel=canonical
What is Canonical URL?
A canonical URL is the preferred, authoritative version of a page. When the same or very similar content is reachable at multiple URLs — tracking parameters, http vs https, trailing slashes, print versions — a rel="canonical" tag tells search engines which one to index and consolidate signals onto.
Setting canonicals correctly prevents duplicate-content dilution, where links and relevance get split across URL variants instead of concentrating on one. Each important page should self-canonicalize, and variants should point to the master.
Canonical tags are a strong hint, not an absolute command — engines can override them if signals conflict — so they should be consistent with your internal links, sitemap, and redirects.
Why it matters
It prevents duplicate content from splitting your ranking signals across URLs.
Canonical URL — FAQ
When do I need a canonical tag?
Whenever the same or near-identical content is reachable at more than one URL — parameters, pagination, syndication, or protocol/slash variants. Point them all at the single preferred version.
Is a canonical the same as a redirect?
No. A redirect sends users and crawlers to another URL; a canonical keeps the page accessible but tells engines which version to index and credit.
Related terms
Internal Linking
Internal linking is connecting your own pages with contextual links to spread authority, guide crawlers, and help users navigate.
Crawl Budget
Crawl budget is the number of pages a search engine will crawl on your site in a given period, set by crawl rate and crawl demand.
Programmatic SEO
Programmatic SEO is generating many targeted, templated pages from structured data to capture long-tail search demand at scale.
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