Many times organizations inadvertently produce duplicate versions of the same web page across various sections of their website, or across various websites. The search engines have become increasingly adept at filtering out duplications in the SERPs to give users varied, relevant results. It is recommended that any duplication be removed from your site. If the duplications are on another domain, remove the content and have the page use a 301 redirect to its corresponding duplicate on the domain you intend to rank. These best practices are really nice to know, but for a myriad of reasons many organizations can not implement them. Usually this failure derives from a cumbersome CMS and it is a common issue with ecommerce sites. The next best solution is the canonical link element.
The Canonical link element can be found in the HEAD section of the HTML document, and correctly references the actual URL that your organization wants to be indexed. Let’s take the following example URLs that are all duplicate pages.
http://domain.com/category/product.html *I want this page to rank*
After some discussion with your team, you decide that the first URL is the page that needs to be indexed. You would put the following tag on the pages you do NOT want indexed.
<link rel=”canonical” href=”http://domain.com/category/product.html”/>
This will give the “credit” to the correct page, and eliminate any ambiguity as to which page the search engine should index.