As I was on my iGoogle page this morning, I clicked on the story “Clinton Preparing to Drop Out of Presidential Race” on ABC News. As I read the story, I noticed they had used some good internal linking practices (i.e. linking to other pages on your site, associating the anchor text content with your other established pages, etc.)… but I also found something wrong: ABC News has URL domain canonicalization issues.

What is URL domain canonicalization and why is it important? Well, canonicalization is the process of picking the best URL when there are several choices. In the ABC News story, you’ll see that they’re linking to a ‘www-version’ page in one internal link… and then linking to a ‘non-www version’ of another page on their domain.

Technically, search engines think your hypothetical homepage of http:///thisisyourdomain.com/ and http://www.thisisyourdomain.com/, both of which are the same page that has the same content, as two separate pages. This is also the case for a thisisyourdomain.com/index.html being the same as simply a clean thisisyourdomain.com/ URL. Obviously, this is a bad thing seeing as how search engines can (and do!) penalize sites for having ‘duplicate content.’

While many, many sites have this issue, it isn’t 100% known that your site could be penalized if you haven’t canonicalized your site. That being said, wouldn’t you like to be 100% sure that you won’t ever receive a duplicate content penalty…?

Pick your favorite URL structure (www or non-www) & canonicalize your site. Ensure that your site won’t be hit by a duplicate content penalty.