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Canonical Tag

Canonical Tag Feature - Must for Good SEO CMS

What is Canonical Tag?

In some cases there may exist duplicate pages and subsequently duplicate content in websites due to site structure and coding. Placing Canonical tag helps us to avoid this. A canonical tag is a special tag that is inserted into the header of your HTML that helps communicate to search engine the relationship of that piece of content to others on your site. Canonical tags tell the search engine bots which pieces of content are the original or primary ones and which are duplicates. This way the bot will pass over the duplicates and only index and give link credit to the primary piece.
 
The syntax is pretty simple:
A duplicate url say http://www.example.com/b.html can specify in the HEAD part of the document the following: <link rel="canonical" href="http://example.com/a.html"/> That tells search engines that the preferred location of this url (the “canonical” location, in search engine speak) is http://example.com/a.html instead of http://www.example.com/b.html.
 

Here's a Explination about Canonical Tag by Matt Cutts of Google

 
Why it is important?
Any website may have multiple URLs for same page like - 
  1. Main Content Page - http://example.com/a.html
  2. Content Index page - http://example.com/index/a.html
  3. Category page - http://example.com/category/a.html
  4. Tag Page - http://example.com/tag/a.html
  5. Print Page - http://example.com/print/a.html
  6. Session ID page - http://example.com/a.html?sessionid=1421
When this happens, site owners suffer rankings and traffic losses and engines suffer lowered relevancy as Search engines don't know which page is original and which one is duplicate. There we need canonical tag to tell search engines which page is original and which one is duplicate.
 
Where to be placed?
In a situation where http://www.example.com/b.html is a duplicate of http://www.example.com/a.html, the canonical tag <link rel="canonical" href= “http://www.example.com/a.html " /> should be placed.
  1. Ideally should be placed in both the pages. 
  2. Mostly be placed in http://www.example.com/b.html.&nbsp;
 
Two important questions to ask for your website:
  • Is canonicalization happening automatically if the Canonical field is blank?
  • Can canonicalization be over written manually?

How Techshu's "Marketing ready CMS" takes care of canonical tags:

In our CMS we have seprate field for adding canonical tags, and if its left blank then canonicalization happens automatically so that you dont have to worry about duplicate content issue, also its so flexible that you can even write your own tag manually.