Definition
Canonical — A canonical URL is the preferred version of a page among a set of duplicate or near-identical pages, declared with the <link rel="canonical"> element.
Quick answer
Give every indexable page an absolute self-referencing canonical; point duplicates to the main version. Canonical is a signal, not a directive — Google may choose a different URL.
Why it matters for SEO
When the same content is available at several addresses (parameters, filters, with and without a trailing slash, HTTP/HTTPS), signals are split between them. The canonical helps the search engine consolidate signals on one URL and show the right address in results.
How it works
Google selects the canonical URL from several signals: rel="canonical", redirects, sitemap inclusion, internal links, HTTPS. When the signals conflict, your hint may be ignored.
<link rel="canonical" href="https://garbuz.online/en/seo-wiki/canonical/" />Common mistakes
- a canonical pointing to a noindex, redirected or 404 page;
- every paginated page canonicalised to page 1;
- relative URLs or URLs with tracking parameters;
- a canonical that contradicts hreflang (each language version must be canonical to itself).
How to check
The URL Inspection tool in Google Search Console shows both the declared canonical and the one Google selected. A crawler (e.g. Screaming Frog) finds canonicals that point to non-indexable pages.
Frequently asked questions
Canonical or a 301 redirect?
Sources
- How to specify a canonical URL with rel="canonical" and other methods — Google Search Central