Member Avatar for shennon

Hey Guys,

Google has recently released a new type of <link> attribute. It's the rel="canonical" attribute. This attribute is used to specify a preferred domain, so that Google bots don't penalize you for duplicate content.

This is very useful for dynamic sites and forums.

Read more here: googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html

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Good thread — useful follow-ups below that build on what and started and answer ’s PageRank question.

Rel="canonical" — quick how-to and practical rules:

  • Put a single, absolute canonical URL in the page <head> for each duplicate/variant and prefer self-referencing canonicals on the canonical page.
  • For non-HTML files (PDFs, etc.) use the HTTP Link header with rel="canonical".
    Example implementations:
<link rel="canonical" href="https://www.example.com/preferred-page/" />
Link: <https://www.example.com/file.pdf>; rel="canonical"

These methods and placement rules are covered in Google’s canonicalization guidance. (developers.google.com)

Behavior, best practices and gotchas:

  • Treat the tag as a strong signal a search engine will usually follow, but not an ironclad command — search engines may pick a different canonical if stronger signals contradict your choice.
  • Redirects (301) are the strongest way to deprecate a URL; rel=canonical is the right tool when you need variants to remain accessible (tracking params, faceted nav, print/mobile views).
  • Never canonicalize to a page that’s blocked by robots.txt or marked noindex; prefer HTTPS canonical targets and keep internal links and sitemaps consistent with your declared canonicals. Avoid chains, multiple canonicals on one page, or conflicting signals across headers/sitemaps/links. (developers.google.com)

Troubleshooting and PageRank / signal consolidation:

  • Canonicals consolidate link/signals in most cases (similar effect to redirects) but engines can override them, so if Google/Bing ignore your tag align stronger signals (internal links, sitemap entries, redirects). Use Search Console’s URL Inspection to compare “user‑declared canonical” vs “Google‑selected canonical,” and crawl the site with a tool (Screaming Frog, site crawler) to find mismatches. If you need a permanent move, prefer a 301. (searchenginejournal.com)

Checklist: canonical = absolute URL in <head> (or Link header for non-HTML), canonical target returns 200 and is indexable, internal links + sitemaps point to the same URL, avoid conflicting rules.

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Member Avatar for jreseo

Yahoo and Microsoft are also supporting this.

This is a very important feature for anyone who has problems with canonical URLs. Rather than a mess of 301 redirects, robots tags, rewrites, etc, you can just state the canonical URL for each page and let the search engines figure it out.

It will be very interesting to see how this could help rankings for a site. It should, since Google does say it will refocus page rank like a 301 redirect, which would make a big difference.

Member Avatar for Robdale

Thanks shennon, The new attribute rel="canonical" is really helpful. But, Does it affect the Page Ranking?

Member Avatar for Dani

Awesome, thanks :)

Member Avatar for sam09

Yahoo and Microsoft are also supporting this.

yep, I also read about it one another blog.

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