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Canonical URL

Declaring the Canonical URL Can Help Your Ecommerce SEO


Ecommerce websites suffer from a unique situation that makes ecommerce SEO difficult: the exact same content is available at different URLs.

Recollect the repeated content problem I mentioned in the article on the problems of SEO for ecommerce websites? This problem is created because different customers navigate ecommerce websites differently.

For instance, take the example of the product: Green Mickey Mouse Umbrella. This umbrella could be reached in a wide variety of navigational paths:
  • Raingear - Umbrellas - Children's - Disney Products - Green - Green Mickey Mouse Umbrella
  • Children's Products - Accessories Raingear - Green Mickey Mouse Umbrella
  • Disney Products - Umbrellas - Green Mickey Mouse Umbrella
  • Seasonal Products - Children's - Comic Characters - Green Mickey Mouse Umbrella
For the purpose of assisting customers locate their place in the navigation tree, ecommerce websites will often display the breadcrumb trail at the top of the page. But some will go a step further and create URLs that reflect the navigation path of the customer. As a result, the above 4 paths would result in the same webpage, but with distinct URLs:
  • http://www.EcommerceWebsite.com/Raingear/Umbrellas/Childrens/Disney-Products/Green/Green-Mickey-Mouse-Umbrella
  • http://www.EcommerceWebsite.com/Childrens-Products/Accessories/Raingear/Green-Mickey-Mouse-Umbrella
  • http://www.EcommerceWebsite.com/Disney-Products/Umbrellas/Green-Mickey-Mouse-Umbrella
  • http://www.EcommerceWebsite.com/Seasonal-Products/Childrens-/Comic-Characters/Green-Mickey-Mouse-Umbrella
Providing users with such URLs has many advantages:
  • Since the URL reflects the navigational path that the user followed, it makes them more confident that they are on the right page.
  • The URL creates a context for the page that the user has landed on. The thought process that the customer followed is validated based on the URL.
  • The alternative products that would be displayed to the customer would be based on the path that the customer followed. For instance, someone who started out with Raingear could also be shown raincoats and rain shoes. While the person who started out with Disney Products could be shown Disney movie DVDs.
So, we have established that displaying the same page at different URLs can make sense. But this innovative architecture creates an SEO problem: search engines locate the same content at multiple URLs. And one thing we know after Google's Panda update is that duplicate content penalties can be quite severe.

This presents the most common dilemma about SEO architecture: do you develop websites for human beings or for search engines? While it seems unforgivable to forsake the human reader, SEO compulsions make it impossible to ignore the search engine either.

Luckily, you can have it both ways. In recognition of the fact that there could be genuine reasons for a website to have the same content present on different URLs, search engines came up with a solution. Welcome to the world of canonical tags.

What you can do is identify one of the URLs as the primary URL, or as we will call it, the canonical URL. Then, in all the other pages that are identical, you can use the canonical tag to inform the search engine about the URL of the original (canonical) version of the page. This eliminates the so-called duplicate-content penalty.

Implementing the Rel="Canonical" Tag
One of the easiest ways to implement the canonical tag is to include a "Link" directive inside the "Head" section of a webpage. Assuming that you wanted to indicate that

is the original URL, you would place the following:
<link rel="canonical" href="http://www.EcommerceWebsite.com/Disney-Products/Umbrellas/Green-Mickey-Mouse-Umbrella/">

In the Head section, i.e., between the tags

Place the rel="canonical" declaration on all the pages which are similar to the canonical page. In fact, it might be a good idea to place the canonical tag on the original page itself. When that page is called with search parameters or session ids, the canonical tag indicates the original version of the page to search engines, thereby completely eliminating this type of duplicate content problem from your website.

Important Notes About the Rel="Canonical" Tag
1) The concept of the canonical tag was introduced a couple of years ago. But the concept of canonical content has existed forever. Earlier, search engine algorithms would try to decipher the canonical content by themselves. By using the canonical tag, you can great assist and influence the search engine in figuring out the canonical content.

2) Though the example on this page assumes identical products, you can use the canonical tag on pages that are not identical, but highly similar. For example in the case of the Mickey Mouse Umbrella, there is a good chance that the content on variants in pink, blue, white, and black would have similar page content. Those pages would be good candidates for including the canonical tag too.
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