Canonical URLs - new SEO Trick?

[Guard Dog]

There is a really good article on SEOMoz about this. Very interesting stuff:

The announcement from Yahoo!, Live & Google that they will be supporting a new "canonical url tag" to help webmasters and site owners eliminate self-created duplicate content in the index is, in my opinion, the biggest change to SEO best practices since the emergence of Sitemaps. It's rare that we cover search engine announcements or "news items" here on SEOmoz, as this blog is devoted more towards tactics than breaking headlines, but this certainly demands attention and requires quick education.
To help new and experienced SEOs better understand this tag, I've created the following Q+A (please feel free to print, email & share with developers, webmasters and others who need to quickly ramp up on this issue):
How Does it Operate?
The tag is part of the HTML header on a web page, the same section you'd find the Title attribute and Meta Description tag. In fact, this tag isn't new, but like nofollow, simply uses a new rel parameter. For example:

<code><link rel="canonical" href="http://www.seomoz.org/blog"></code>​

This would tell Yahoo!, Live & Google that the page in question should be treated as though it were a copy of the URL SEOmoz Blog | Search Engine Marketing News & Tips and that all of the link & content metrics the engines apply should technically flow back to that URL.

See full article here: SEOmoz | Canonical URL Tag - The Most Important Advancement in SEO Practices Since Sitemaps


Good stuff! There is a lot of infromation there and it is VERY wise for those who do their own SEO work to read and understand this type of link.

 

[sipka]

Thanks Andy for this interesting read. What I don't get at the moment, that how can I give the "duplicated" pages this head element, as most of the times these duplicated pages aren't created on purpose, but they are built by some kind of CMS permanent link weird mode that you can (or cannot) regulate by a .htaccess file and with mod rewrites.
So I like this idea in theory, but practically these duplicate pages usually are not human generated, so how one can add this "rel" attribute when you didn't even create the given page directly?

I need to think this over lol.

 

[Guard Dog]

Well, a number of popular CMS and Blog tools already have a plugin to do this for you That way you don't have to hunt down the location for each canonical URL and place it yourself.

 

[WagerX]

Thanks Andy,
I just watched a SEOMOZ white board Friday about using the hash symbol to help canonicalization as well. It's relevant to this so here's the url:SEOmoz | Whiteboard Friday - Using The Hash in URLs for SEO

Waht the video is about is using the "#" instead of the "?" in a url so the search engines ignor what's after the "?" thereby eliminating the perception of duplicate content.

EX: xxxhttp://www.myurl.com?user=1
EX: xxxhttp://www.myurl.com?user=2

Are viewed as 2 different pages with duplicate content, where as these:
EX: xxxhttp://www.myurl.com#user=1
EX: xxxhttp://www.myurl.com#user=2

are just considered one page.
I am sure you could define this in a canonical url tag, but implementing this in standard practice (or at least being conscious of this) helps.

This has more significance to webmasters who use CMS and the affiliate programs themselves.