Throughout my journey as a Web Developer, the most common Search Engine Optimization (SEO) oversight I have come across is URL Canonicalization.

According to me, this is an important task that all website owner’s should be aware of as well as have the capability to easily fix.

In my terms, I would explain canonicalization as your domain name having several links all leading to the same content page. For example, all domain names will have at least two versions:

1. With www. – http://www.url.com
2. Without www. – http://url.com

Plus, depending on how your site was built you could also have other domain versions that lead to the same content page:

• http://url.com/index.php
• http://www.url.com/index.php
• http://www.url.com/index.html
• http://url.com/home.asp

What this means is that your site can actually be indexed as multiple sites through each of these domains instead of as one site. The implications that this issue could pose are numerous – however, if you are simply not aware that this has happened and have not done anything sneaky to try to trick the search engines, from my understanding you will not be penalized.

Some of the implications I have come across include:

• Not being able to generate true web analytics reporting: as visitors will be viewing your site from different domains.
• Not being able to get a ranking on Alexa.com as perhaps these multiple entry points to your site are affecting your main domain’s true value.
• Not getting a good grade on your website through hubspot’s website grader tool – again – not enough data being truly measured by your main domain.
• Not being able to gather enough statistics in your Google Webmaster Tools & Google Analytics account to fully take advantage of the features of these tools.
• Not generating the proper backlinks to your main domain as people may be linking to multiple versions of your site instead of your main domain.

I am sure that there are indeed other implications that I am not thinking of right now…

Nevertheless, the best way to address any issues your site may have with url canonicalization is to read the article titled “SEO advice: url canonicalization” written by Matt Cutts at Google.

As he explains, setting up an account with Google Webmaster Tools is your ultimate starting point.

Plus, be sure to read the Google Webmaster Central blog post “Specify your canonical“.

Also watch this video by Matt Cutts: About rel=”canonical”