Top 3 Search Engines Unite on Canonical URL

Google, Yahoo and Microsoft join hands in the drive to clean up the web of duplicate contents. The top three search engines are implementing support for the new HTML tag – “<link>” .

The new <link> tag defines the relationship between a document and an external resource that results to the site’s canonical or preferred URL form that would encompass all the sub-domains and variations of a website. The <link> tag will tell search engine crawlers which canonical URL form it will use when retrieving search results.

The <link> tag also putt the Canonical URL for at the forefront of the website content which will be used for accessing the page,  regardless of the session id, link parameter, sort parameter, parameter order of the URL form.

To implement Canonical URL form on website, site owners just need to add the following link tag at head section of the site’s HTML.

<link rel=”canonical” href=”” />

By adding the link tag, the search engine crawlers  will disregard the following URL variants but have the same contents as the identified Canonical URL form:

The Live Search Blog, Google Webmaster Blog, and Yahoo Search Blog identified some technical details to consider when implementing the <link> tag on your sites.

Arnold Zafra
Arnold Zafra writes daily on the announcements by Google,, Yahoo & MSN along with how these announcements effect web publishers. He is currently building three niche blogs covering iPad News, Google Android Phones and E-Book Readers.
Arnold Zafra

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9 thoughts on “Top 3 Search Engines Unite on Canonical URL

  1. Just a little nitpick here – the tag is not used, its been around for a long time and used for things link stylesheets and rss feeds. The new part is the “canonical” part in the “rel” attribute.

  2. From Yahoo: “The tag will be treated similarly to a 301 redirect, in terms of transferring link references and other effects to the canonical form of the page.”

    I hope google treats it that way too… then the need for no-follow PR sculpting goes away for many sites!

    I’ll probably be testing this over the next month…

  3. Important! If you’re going to do this – for the love of God please set your canonical version to NOT have an unneccessary “www.” prefix. It just makes links longer, takes longer to tell someone about, and takes longer to type. Not to mention making it less likely to fit in a tweet 😉

  4. I study CSS2 and that “canonical rel” is totally new to me. Is it a specification of CSS3? If so they can I use it now? I have been using link all the time. Not this canonical. That’s guru talk right there.

  5. Good idea. Search Engine’s crawlers did not indexing same web page but different Urls. But, what is the major different between canonical and 301 redirects?