The canonical link element has been around for nearly three years. Apart from protecting your website from duplicate content, it has the power to take advantage of otherwise hard to get links. I can't get my head around why there are so many sites with affiliate and partner programs, missing out on their most valuable links.

First, I would like to introduce you to one particular case, where rel=”canonical” solved not one, but two problems. A website I work for has this bizarre tracking system, where subdomains are used for tracking. When a partnership is formed, we give the partner a link similar to this one – greatpartner.lnk.visafirst.com. It loads a copy of the main site www.visafirst.com. When I took over the SEO for the business I was amazed how many links are rendered useless. Because of these powerful links from our partner, the tracking subdomains were ranking higher than the website itself.

At that time the company could not spare the resource to rewrite the whole tracking system and contact each partner with new URLs, so I was left with the hard decision to have <meta name="robots" content="noindex, nofollow"> on all subdomains, throwing away our most valuable and relevant links.

When I heard about the canonical link element in February 2009, I immediately had it placed on all of our tracking subdomains. We removed the “noindex, nofollow” and after only two weeks the links became visible on webmaster tools. Rel=”canonical” worked like a charm, taking care of duplicate content and giving us the much needed links!

Links form pages having rel=”canonical”

I understand our tracking system dates from the Bronze Age. I’m afraid it will stay like this for the next couple of years. At this point you might be asking yourself – how can this help a modern-day tracking system. Well, it turns out that even big sites are not milking this. Have for example www.worldnomads.com.

Anyworkanywhere.com participates in their affiliate program and links to them with

http://www.worldnomads.com/index.aspx?affiliate=AN...

If you check the source or run SEOmoz’s On-Page Optimization Report, you will see no trace of canonical implementation.

Result excerpt from SEOmoz’s On-Page Optimization Report

This means that this page is clearly duplicate content and it a good links is somewhat wasted. World Nomads is sitting on a gold mine of links and they are not taking advantage of them.

By placing rel=”canonical” or your affiliate URLs you gain links with each new participant.

One of the best examples for appropriate use of the canonical link element is Amazon. This URL is taken from a random hub on hubpages.com.

http://www.amazon.com/Digital-Stylus-Tablet-rohs-M...

The source of the page show they take advantage of the canonical link element. Amazon let the search engine know that this page is actually a copy of

http://www.amazon.com/Digital-Stylus-Tablet-rohs-M...

If you have a good affiliate program running, do implement rel=”canonical” to boost your link profile.

Further readings on Rel Canonical can be found here:

• Guide to Rel Canonical by Lindsay
• SEO advice about the canonical link element by Matt Cutts
• 20 minute video about canonical by Matt Cutts