Making Use Of The New Canonical Tag Within eCommerce SEO
By Craig Smith
Earlier this year, search engine representatives across all three main search engines, released a statement to announce a uniform method for reducing duplicate content. All three (Google, Bing, Yahoo) announced that they would embrace a "canonical" tag that would assist search engines in understanding primary URL's within a domain.
In ecommerce environments, where navigation paths can lead to as many as 15 URL's for a given product page, this development is a major step to better structure your site for optimal search engine optimization.
Essentially, this “canonical” tag, is included inside the HEAD of any HTML document. When properly leveraged, the tag is now the most effective way to reduce the negative impact that can happen when the same page is indexed multiple times under a variety of URL’s.
This tag is basically conveying to a search crawler, “Googlebot, this URL you are on isn’t the preferred page for this content, href=http://mysite.com/page1.html is.”
In talking to representatives within the engines as well as retailers alike, duplicate content is a paramount issue and this tag will definitely kickstart actions on both sides to improve website indexing.
Here's a real life example. You can have the following example variations for a fictional website:
So which is the primary page? All of these pages can be indexed, but which version should an engine render?
You can try using 301 redirects to fix, but sometimes these are tough to generate depending on the sophistication of your CMS or eCommerce platform.
You could eliminate URL parameters such as session ID’s and tracking codes, but then you are losing data to help you gauge the impact of your marketing and do not really leverage your analytics optimally. In this situation, use the canonical tag!
How does this impact your SEO efforts? Unlike a 301 which redirects all web traffic, the canonical tag is an indicator for only engines which allows you to keep your existing url.
It will help engines in concentrating link equity into one primary URL, for a specific piece of content, as well as essentially tell them which page you want to have as the “authority” page...while at the same time, not affecting your visitors and their experience in any way.
Want some facts right from Google? Here are answers that they published in their webmaster central blog: http://googlewebmastercentral.blogspot.com/2009/02/canonical-link-element-presentation.html
From: Practical eCommerce: http://www.practicalecommerce.com/blogs/post/587-Making-use-of-the-new-Canonical-tag-within-eCommerce-SEO