Here is a good link on the subject:
Source:Q: What is a canonical url? Do you have to use such a weird word, anyway?
A: Sorry that it’s a strange word; that’s what we call it around Google. Canonicalization is the process of picking the best url when there are several choices, and it usually refers to home pages. For example, most people would consider these the same urls:
* http://www.example.com
* example.com/
* http://www.example.com/index.html
* example.com/home.asp
But technically all of these urls are different. A web server could return completely different content for all the urls above. When Google “canonicalizes” a url, we try to pick the url that seems like the best representative from that set.
Matt Cutts: Gadgets, Google, and SEO
Here's how my electronic dictionary defines canonical (the relevent definition out of several): Reduced to the simplest and most significant form possible without loss of generality
So what am I doing? I am now using a 301 (permanent) redirect. If you try to access the CSE HTML Validator website with htmlvalidator.com instead of http://www.htmlvalidator.com, it should now redirect to the http://www.htmlvalidator.com domain. Try it out.
Information about how to do this is here:
http://www.google.com/#hl=en&source=hp& ... 88018abe0f
I now use this in my Apache config file:
Code: Select all
RewriteEngine on
RewriteCond %{HTTP_HOST} ^htmlvalidator\.com
RewriteRule ^(.*)$ http://www.htmlvalidator.com$1 [R=permanent,L]