SEARCH ENGINES UNITE TO REDUCE DUPLICATE CONTENT
Google, Yahoo and Microsoft have coming together in rare agreement on a standard for identifying canonical links to reduce the impact of duplicate links through the introduction of a new HTML tag: <link>. This new <link> tag helps reduce duplicates by documenting the preferred URL form to access each page. Duplicates can come about for multiple reasons; common ones include sorting the page by parameters (eg price), or tracking codes for identifying the referring source of traffic in web analytics sofware.
As an example for one our clients, the following 3 URLs are all valid for the same page. Using the new tag, we can specify the official/canonical version that we want to be indexed and displayed in the search results.
http://www.goldenglow.com.au/product.asp?pID=57&cID=11
http://www.goldenglow.com.au/product.asp?pID=57
http://www.goldenglow.com.au/product.asp?cID=11&pID=57
For more gory details, check out:
Google’s announcement and explanation
Yahoo’s announcement and explanation
