Google and the Canonical Link Rel
Google has introduced a link tag rel value of canonical which is used for defining the value of the page that Google should use. Why? Lets say you have an eCommerce site and one of the product URLs is:
http://yoursite.com/product.php?p=david+walsh+blog+book
Imagine now that you can make a slight customization to the product that changes the URL to:
http://yoursite.com/product.php?p=david+walsh+blog+book&color=red
Uh oh -- Google sees duplicate content! The code shows essentially the same page so Google thinks you're pulling gangsta stuff. Now you can tell Google what URL to use for the current page to avoid duplicate content penalization.
The XHTML
<link rel="canonical" href="http://yoursite.com/product.php?p=david+walsh+blog+book" />
Don't let your website get penalized by Google; use this link/rel tag combination for your highly variable pages.
![CSS Gradients]()
With CSS border-radius, I showed you how CSS can bridge the gap between design and development by adding rounded corners to elements. CSS gradients are another step in that direction. Now that CSS gradients are supported in Internet Explorer 8+, Firefox, Safari, and Chrome...
![An Interview with Eric Meyer]()
Your early CSS books were instrumental in pushing my love for front end technologies. What was it about CSS that you fell in love with and drove you to write about it?
At first blush, it was the simplicity of it as compared to the table-and-spacer...
![Image Protection Using PHP, the GD Library, JavaScript, and XHTML]()
Warning: The demo for this post may brick your browser.
A while back I posted a MooTools plugin called dwProtector that aimed to make image theft more difficult -- NOT PREVENT IT COMPLETELY -- but make it more difficult for the rookie to average user...
![Facebook Open Graph META Tags]()
It's no secret that Facebook has become a major traffic driver for all types of websites. Nowadays even large corporations steer consumers toward their Facebook pages instead of the corporate websites directly. And of course there are Facebook "Like" and "Recommend" widgets on every website. One...
Note that the All-in-one SEO WP plugin does this for you. Good to know should you bloggers be worried.
I think the article could have given a bit more info on canonical urls…
@Adriaan: Thank you for your comment. I could have but my fear is spending a ton of time on an explanation when 99% of people would prefer a brief explanation with a sample problem and solution like I provided. I appreciate your honesty!
OK, I had to go to Google to find out where in the document this LINK goes… But this is good info, thanks for the the tip. Google implies that some other search engines look at this too.
time to google for more about canonical ;)
Cool information!
Liked the posts about firefox extensions too, really useful for beginners on that world.
ps: you forgot to close the link tag.
Add this code to the section of the page.
< head >
< title > Davidd Walsh Blog Book< /title >
< link rel=”canonical” href=”http://yoursite.com/product.php?p=david+walsh+blog+book” />
< /head >
@Fabio, No missing < /a > tag as its a < link .. >
Good I want to implement it first and have post this tips. Thanks
great post is there any problem if i use rel tag for all of my links
David,
Thanks for the tip about rel canonical.
Peter
You can find more info here: http://support.google.com/webmasters/bin/answer.py?hl=en&answer=139394
Thanks for the article.