One of the most ignored SEO aspects is URL canonicalization.
Many people get confused by this term and do not really understand its purpose.
In reality, it is quite simple to understand the role of this process.
What is URL canonicalization?
URL canonicalization refers to the process of picking the best URL when there are multiple choices. This process is designed to help search engines to choose the best version of a site or of a specific page.
Canonical URLs For Domain Name
Each website can be accessed even with www before domain name or without www. Both should take you to the same page and will not greatly influence human visitors browsing experience.
However, things are changing from the perspective of search engines. Search engines see the www version and the non www version like two completely different versions of your website.
Search engines see the following examples different:
When the search engines bots access your website and when it can be accessed in both versions, they are trying to determine which is the best version of your website. Using non canonical URLs can lead to page rank and authority dilution that can occur if search engines can’t determine which version of your URL should be preferred or if your site’s backlinks are pointing to both www and non-www version.
Canonical URLs For Pages
The same principle applies to the pages of your website.
There are several reasons why some pages can be seen as duplicate. Some dynamic generated pages can add additional filters/variables or user session to URL.
Basically, these pages will display the same content only in a different order.
How To Make A Canonical URL
Best SEO practice is to redirect a version to the other version using a 301 redirect (does not really matter if www version to the non-www or vice versa).
The 301 code will notify search engines that a certain page has permanently moved to a new location and all of the traffic will be redirected to your prefered version.
There are multiple ways to canonicalize a URL.
On Apache servers (Linux), you can add a 301 redirect in your .htaccess file, redirect that will affect all pages.
If you want to move all the pages of your old site to a new domain, you should do a Mass 301 redirect to transfer the authority of the old website to the new one.
If you want to canonicalize only a certain page, you can add a small HTML code inside the < head > tags of that page.
If you have a blog accessible at both http://www.example.com/blog and http://www.example.com/blog/index.html and if you want that search engines to treat these pages as one (and you prefer http://www.example.com/blog ), you will add the following code inside the < head > tags of http://www.example.com/blog/index.html
<link rel=”canonical” href=”http://www.example.com/blog” />
I hope you now better understand what a canonical URL is and how to optimize your links. In the next post I will cover HTML meta tags usage.