Impact Media's SEO Blog

It’s one of those rare occasion when the three major search engines come together in an effort to improve search by agreeing on common standards.

Search Engines Unite With Canonical Tag

This time, it’s the turn of duplicate content and the issue of canonicalisation. Canonical, in this context, refers to the issue of duplicate content and there’s many reasons why this may occur. For legitimate reasons, Google, Yahoo and Microsoft have now agreed a new standard tag to be used in the header section of a web page to specify the preferred URL.

All very good as it will flag up to the search engines and work in a similar way to 301 redirects, i.e. consolidate your link popularity to the preferred location.

Further Reading:

• Search Engine Land: Google, Yahoo & Microsoft Unite On “Canonical Tag” To Reduce Duplicate Content Clutter
• Google: Specify Your Canonical
• Yahoo: Fighting Duplication
• Microsoft: Help Solve Duplicate Content Issues

Apart from being a dreadful word, canonicalisation is an important factor for Webmasters and site owners to consider. Basically, it refers to picking the URL that you want for your primary URL and re-directing the ‘other versions’ to it.

Let’s say you have:

• yoursite.com
• www.yoursite.com
• www.yoursite.com/index.html
• yoursite.com/index.html

Although you would imagine they’re all the same, technically they are different. Potentially, a web server could show a different profile, e.g. links and content, for each of these scenarios.

Try to get into the habit of being consistent with your internal links.

More importantly, go to your web server and set-up a permanent (301) re-direct from the other versions of your domain to the URL format you have selected for your primary.

The search engines are getting better at resolving this issue and Google Webmaster Tools allows you to set a preferred domain. However, you shouldn’t rely on this and instead use a 301 re-direct to ensure that you control which view of your domain you’d like the world to see.