How to use Canonical Tags in Dealing with Duplicate Content.

Whenever a client site is being search engine optimized, the biggest issue faced by SEO experts is duplicate content pages. Most of the Content Management System is known to create several versions of identical content in pages but in some cases there are instances when this procedure is required. This process, however, creates problems for search engines as they are unsure about indexing the pages. Very often the problem is more acute in e-Commerce sites where different pages are generated in slightly different URLs but with the same content. This creates problems for search engines as they see different pages when only one is required to be listed. Another issue being that each page would have a page rank and ideally the SEO experts would want to concentrate all the page ranks on one single page to obtain a higher ranking.


The normal procedure with duplicate content pages is to re-direct all the copies to the original page through “301 Redirect”. A better way of dealing with duplicate content is to use a Canonical Tag which informs search engines to ignore duplicate pages and pass on all the ranking values down to the original page. While using Canonical Tags certain guidelines need to be followed :

01)      Usage of absolute URLs in the Canonical Tag to avoid chances of errors occurring.

02)      The Canonical Tag works only with pages that are similar. However, some alterations are permitted like a different chronological setup in the page content. But too many changes would prevent search engines from indexing the site.

03)      The Canonical Tag is used only across the pages in the same domain.


Nowadays, Google, Yahoo and MSN have come up with this new “Idea” to help Webmasters fight duplicate content. It is quite easy to control duplicate content with Canonical Tags and they appear on a website whenever :

  • More than one page has identical content.
  • More than one page has similar content to some extent.
  • Any page on the website is repeated due to technical glitches.
  • Dynamically generated pages repeat the same content over various issues.


In most of these cases, when search engines see the same content on different pages they “suspend” ranking of those pages and also take time before showing up these pages on search results page. An example being whenever a website has identical content on first two pages, with the exception of the background color, it is dynamically controlled by CSS styles. Hence, Canonical Tags are used in the website in such cases. It is a simple piece of HTML code that is inserted in the “Head Section” of a duplicate page which informs the search engines about its existence and also communicates to the user that they need to find the original content elsewhere and guides them to that particular page.

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