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Canonical URLs Explained

A canonical URL tells search engines which version of a page should be treated as the preferred version when several URLs contain similar content.

Why duplicate URLs happen

The same content can sometimes be available through multiple URLs. Tracking parameters, filters, print versions, alternate paths, and trailing-slash differences can all create URL variations.

  • Review pages with tracking parameters.
  • Check whether both HTTP and HTTPS versions redirect correctly.
  • Make sure www and non-www versions resolve consistently.

What a canonical tag does

A canonical link element is placed in the head of a page and identifies the preferred URL. It is a hint to search engines, not a substitute for redirects or access controls.

  • Use the full absolute URL.
  • Use one preferred canonical URL per page.
  • Keep the canonical URL consistent with internal links and your sitemap.

Canonical tags are not security controls

A canonical tag does not hide a page, block access, or prevent a URL from being visited. If content should be private, protect it with authentication. If a page should permanently move, use a redirect.

  • Use authentication for private information.
  • Use redirects when an old URL should no longer be used.
  • Use noindex only when excluding a page from search is the intended outcome.

Next steps