I just learn from Twitter that Google, Yahoo and Microsoft implemented and announces Last week support for a new link element to clean up duplicate urls on sites. And it is what they called. Canonical Link Element in 5 minutes
What is Canonical Link ?
It is a link that will tell Google to index the permalink of your post and not the duplicate content of your post such as follows :
https://www.techathand.net/gsma-2009-nokia-ovi-store/page3/
https://www.techathand.net/gsma-2009-nokia-ovi-store/page4/
https://www.techathand.net/gsma-2009-nokia-ovi-store/?asdalsdkjalsjda
So with the above example it will tell Google to index https://www.techathand.net/gsma-2009-nokia-ovi-store/ and not the other URL mentioned above.
So What is the Solution ?
I am not really that fun of installing lots of plug-ins in my site so if I can make it in PHP it will be better. Since the link should be inserted in the head part of the post I made this php code inserted in my header. { It means put it before </head> part of the header code }
<link rel="canonical" href="<?php the_permalink() ?>" />
I think it works since even if I test it my other blog post it still shows the permalink as the canonical link.
But if you don’t want to mess your Header Codes from WordPress you can install plug-ins. The Yoast Plug-in did not help me since it is clashing with my other plugin and I believe a simple code as shown above works.
Source : mattcutts.com , marhgil & noel bautista