Duplicate page/url problem has been around for half a decade now. And still the confusion among site owners and webmasters float around. There is so many authentic and easy to understand articles on rel=”canonical” that it will be useless to talk about them all again. Rather I decided to put a reference of all such authentic sources in one place.
http://en.wikipedia.org/wiki/Canonical_link_element
https://www.mattcutts.com/blog/canonical-link-tag/
https://support.google.com/webmasters/answer/139066?hl=en
http://googlewebmastercentral.blogspot.com/2013/04/5-common-mistakes-with-relcanonical.html
http://googlewebmastercentral.blogspot.com/2011/06/supporting-relcanonical-http-headers.html
http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html
http://blogs.bing.com/webmaster/2012/04/27/better-than-canonical-url-normalization/
http://moz.com/learn/seo/canonicalization
http://moz.com/blog/rel-confused-answers-to-your-rel-canonical-questions
http://moz.com/blog/dispelling-a-persistent-rel-canonical-myth
https://yoast.com/articles/duplicate-content/
Webmaster Tool Videos on Canonical URLs by Matt Cutts:
What are the advantages of 301 redirects over rel=”canonical”?
[one_half]In the 2009 rel=canonical video, you suggest using rel=canonical when we CAN’T use a 301 redirect. But 301s hurt performance; they require browsers to make an extra round-trip to my servers. Shouldn’t I use rel=canonical everywhere, instead of 301s?
Dan Fabulich, San Francisco, CA | Published on Dec 11, 2012[/one_half][one_half_last][/one_half_last]
Do robots follow links on a page which uses rel=”canonical” to point to a different page?
[one_half]On a website, if a page B implements a rel=”canonical” link tag with URL of page A, do robots follow every links in page B? Ad, Paris | Uploaded on May 25, 2011[/one_half][one_half_last][/one_half_last]
Will setting the rel=”canonical” attribute of a page to itself cause a loop?
[one_half]Hi Matt, With canonical tags can you point a page to itself.? So if www.google.com/webpage points to www.google.com/webpage will this cause a loop? Mark James, Yeovil UK| Uploaded on May 25, 2011[/one_half][one_half_last][/one_half_last]
Does Google support cross-domain rel=”canonical”?
[one_half]”Hi, how does Google see cross domain canonicals?” Computerklaus, São Paulo, Brazil| Uploaded on Apr 19, 2011[/one_half][one_half_last][/one_half_last]
Is there an advantage to using rel=”canonical” over a 301 redirect?
[one_half]Hey Matt. I had a lingering question about using rel=canonical vs. 301 redirects. It takes longer for Google to find the rel=canonical pages but 301 redirects seem to lose impact (link juice) over time. Is there similar churn with rel=canonical? Sam Crocker, London, UK | Uploaded on Apr 11, 2011[/one_half][one_half_last][/one_half_last]
Can I use rel=canonical when publishing articles on different sites?
[one_half]bflicker from Los Angeles, CA asks: “If we were to syndicate my written content (entire articles) to multiple domains then would we be able to use the imminent cross-domain link rel=”canonical” tag to confirm which site we would like to index for a given piece of content?”
Note: This video was recorded on December 4, 2009. We have since officially announced support for cross-domain uses of rel=”canonical”. Please see this blog post for more information:http://googlewebmastercentral.blogspot.com/2009/12/handling-legitimate-cross-domain.html | Uploaded on Apr 13, 2010[/one_half][one_half_last][/one_half_last]
http://googlewebmastercentral.blogspot.com/2009/12/handling-legitimate-cross-domain.html
Related Read: Reunifying duplicate content on your website
Saidul Hassan