Google have recently introduced a new link element which people can use to avoid duplicate content.
Internal duplication is a very serious issue that most webmasters have to face.
Example of internal duplicate pages:
There are many forms of internal duplication. Let’s start with the home page of a site.
A site can be accessed by these URLs [depending on the used language]:
www.site.com/
site.com/
www.site.com/index.php
site.com/index.php
www.site.com/index.html
site.com/index.html
www.site.com/index.asp
site.com/ index.asp
All the above mentioned URLs will get us to the home page of a site and all of them will display the same content. Isn’t this going to produce duplicate issue? Well, it will.
Here is another example:
Forum scripts produce lot of duplicate content issue. Same page is accessed by many URLs.
For example:
someforum.com/index.php?id=1
someforum.com/index.php?id=1&page=1
someforum.com/index.php?id=1&sortby=2
someforum.com/index.php?id=1&sortby=2&page=1
someforum.com/index.php?id=1&sortby=2&page=1&mode=threaded
someforum.com/index.php?id=1&page=1&mode=threaded
someforum.com/index.php?id=1&mode=threaded
someforum.com/index.php?id=1&pid=44
All the above mentioned URLs [plus there can be many more], will give us the same content. This creates so much trouble for search engines and this creates problems for webmasters who want their sites to be easily and correctly accessed by SEs.
To tackle this major problem, Google has introduced a new link element. This tag will end the internal duplication problem.
What is this link element called?
It’s called: Canonical Link Element.
How this link element looks like?
<link rel=”canonical” href=”http://www.site.com/” />
What this link element does?
This link element tells search engines to use/prefer the defined link/URL for the respected page.
For example:
I showed some links that forum scripts can use. The correct/basic URL is:
someforum.com/index.php?id=1
But this page can be accessed by many other URLs. Now the link element will tell search engines to use/prefer only this URL for the respected page:
someforum.com/index.php?id=1
And ignore all other URLs that show this page’s content.
How to use this link element?
You only have to put this code in the head section of your page code:
<link rel=”canonical” href=”Preferred URL to Use” />
Preferred URL to Use: here you will put the preferred URL that you want search engines to use.
Do all search engines use this link element?
Matt Cutts talked about this element in a video and he said that Yahoo and Microsoft [MSN] agreed to use this element in the future. Major search engines will use this element but at the moment, I think only Google use it.
