Canonical URL Tag…Good or Bad for SEO?

Author: George Zlatin

February 14, 2009 • Filed Under: Google News, Search Engines • 1 Comment

Big news in the SEO world folks….Google, Yahoo and MSN have recently announced that they will be respecting and following what’s known as the “Canonical URL Tag”. This new tag (if it works) allows you to avoid duplicate content issues by letting the search engines know which pages are duplicate and which are the preferred versions. This is actually a very big deal for SEO’s since it sort of makes our lives a lot easier…we hope. Until now, we’ve had to play the role of duplicate content evangelists. Part of our job was to create complex webs of 301 redirects and noindex pages to handle duplicate URL’s. We have been plagued by pagination, “sort by” features like sort by price, test landing pages, and other similar devices that have been helpful for site visitors but create multiple URL’s for the same or similar content. Now all we have to do is use this tag to avoid a giant duplicate content mess all over the place.

Here’s the technical explanation of how it works quoted directly from Google’s blog:

Now, you can simply add this <link> tag to specify your preferred version:

<link rel=”canonical” href=”http://www.example.com/product.php?item=swedish-fish” />

inside the <head> section of the duplicate content URLs:

http://www.example.com/product.php?item=swedish-fish&category=gummy-candy
http://www.example.com/product.php?item=swedish-fish&trackingid=1234&sessionid=5678

and Google will understand that the duplicates all refer to the canonical URL: http://www.example.com/product.php?item=swedish-fish. Additional URL properties, like PageRank and related signals, are transferred as well.

Some people think that this tag is not that helpful or useful. I think this new tag adds to our toolset and it further solidifies SEO’s legitimacy in Google’s eyes. I can think of multiple uses already that will save a lot of time and help improve clients rankings…I don’t see anything wrong with that.