Canonical Tag
Also known as rel=canonical · canonical URL
A link element that names the preferred URL for a page so search engines consolidate duplicate or similar versions.
What it is
The canonical tag is <link rel="canonical" href="..."> placed in the head, declaring which URL is the authoritative version when the same or near-duplicate content is reachable at multiple addresses. Search engines treat it as a strong hint to consolidate ranking signals onto that single URL.
Why it matters
Canonicalization prevents duplicate-content dilution from query strings, trailing slashes, http/https, and www variations, ensuring link equity and crawl budget concentrate on one URL. For AI answer engines, a clear canonical reduces ambiguity about which version of a page to attribute and cite.
How to verify
View the page source and confirm a single rel=canonical link with an absolute, self-referential URL that returns 200 and is not a redirect or noindex page. Search Console's URL Inspection tool shows both the user-declared and Google-selected canonical for comparison.
How to fix
Add one rel=canonical per page pointing to the absolute, preferred URL, and make important pages self-referential. Ensure the canonical matches the version in your sitemap and is not blocked by robots.txt or noindex, and avoid conflicting signals such as multiple canonicals or canonicalizing to a redirecting URL.
Related terms
- XML SitemapAn XML file listing a site's canonical URLs to help search engines discover and prioritize pages for crawling.
- noindex TagA directive, set via meta tag or HTTP header, that tells search engines to keep a page out of their index.
- robots.txtA plain-text file at the site root that tells crawlers which paths they may or may not request.
- Server-side rendering (SSR)Delivering the page's core text and markup in the initial HTML response, so it is readable without executing client-side JavaScript.
Official references
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