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.
Webmaster Tool Videos on Canonical URLs by Matt Cutts:
What are the advantages of 301 redirects over rel=”canonical”?
Dan Fabulich, San Francisco, CA | Published on Dec 11, 2012
Do robots follow links on a page which uses rel=”canonical” to point to a different page?
Will setting the rel=”canonical” attribute of a page to itself cause a loop?
Does Google support cross-domain rel=”canonical”?
Is there an advantage to using rel=”canonical” over a 301 redirect?
Can I use rel=canonical when publishing articles on different sites?
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
Related Read: Reunifying duplicate content on your website