SEO Duplicate Content Issues – a Canonical Fix at Last

For owners and webmasters of eCommerce websites, the issue of duplicate content is all too common. Usually, for functional and usability reasons a site would have vastly identical pages that are accessible via multiple URLs. Take for example an online store selling sunglasses might have numerous URLs for listing their Ray Ban Wayfarer Sunglasses. They might have URLs specific to brand, price range, colour and style. On a well designed and laid out site, it would be easy for visitors to access product pages, but for search engine bots, it always usually a pain selecting the ‘preferred’ URL to reference in search results. For an SEO professional and for link building, the issue of page rank dilution crops in because a link that could have been attributed to a single page bears the risk of being attributed to one of many pages. Search engine bots tend to crawl less of a site riddled with duplicate content.

Thankfully, duplicate content issue from a multiple URL perspective is a thing of the past due to a long awaited collaboration of Google, Yahoo and Microsoft. The have announced a new ‘canonical tag’.

So what does the ‘Canonical’ Fix Mean?

With the canonical tag (see syntax below), you specify exactly what URL you want indexed in the event of multiple URLs referring to the same content. So if you have 5 URLs referring to the same content (like the Ray Ban Wayfarer Sunglasses), you can specifiy the canonical URL in the head section of that page as follows:

<link rel="canonical" href="http://www.YourPrefferedCanonicalURL.com"/>

And that’s it really !

The canonical tag consolidates old URLs to new URLs in a similar way to a 301 redirect and give search engine bots vital ‘hint’ on exactly what URL to crawl and index.

A Few More Points to Note About the Canonical Tag

• The tag is allowed on a single domain or website – so subdomains and subfolders are permitted.
• Relative or absolute links can also be used, but Google recommends absolute links.
• The tag would only work with very similar or identical content, so spammers intending to pass some link value from one page to another should note this.
• If tags conflict by cross linking the canonical URL to each other, search engine bots with sort indexing and crawling to the way they currently do i.e. they’ll have to determine which URL is the best canonical version.

Further Reading

• Matt Cutts 5 minute explanation of the Canonical link element
• Google’s take on the Canonical link element
• Yahoo’s Take on the Canonical link element
• Microsoft’s take on the Canonical link element
• Google, Yahoo & Microsoft Unite On “Canonical Tag” [Search Engine Land]

Kunle T Campbell

Fuzz One's Head of Search Marketing, he has been involved in the search marketing industry since 2004. He is a Certified Google AdWords Expert, an SEO expert and is highly proficient in website analytics

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