Last week, Google, Yahoo and Microsoft has together introduced a new tag, called ‘Canonical‘  to help clearing duplicate URLs. What is Canonical Tag? The basic principal is to tell search engines, the preferred URL on your site, and telling them out of tonnes of URL pointing to certain web pages on your website, which URL should be indexed.

The tag should looks like this, installed on each of your web page’s <header> section.

<link rel=”canonical” href=”http://example.com/page.html”/>

I have to read the first post that I come across to, many times before I pretty much understand how it works and what for. I know it is going to be quite confusing initially. So you should read Joost De Valk’s post, how he illustrate this tag to his readers.

He in fact has created Canonical URL plugin for WordPress, Magento and Moveable as well, which will add the tag automatically at your <header> section.

If you still confuse, you might as well take a look at Matt Cutt’s presentation.