Reports & Whitepapers

New POV on HTML Tag for Duplicate URLs

February 23, 2009

This month, Google, Yahoo and MSN announced their support for a new tag designed to eliminate duplicate URLs for a given Web site in search engine results. The tag marks a select URL as “canonical,” which means that it is the predominant URL for a page, even if there are two or more similar URLs leading to that same page. The word “canonical” (click here for the pronunciation) describes the “master copy” of something.

Here are some examples of duplicate URLs:


With the canonical tag, search engine marketers can more effectively control the URL returned in their search results. More importantly, the page will do better in search results because the master URL will consolidate all of the authority that was previously distributed and diluted between multiple URL versions of the same content.

The new tag can be easily added to an existing site by adding it to the page in the form
<link rel=”canonical” href=”[master URL here]” />. The canonical tag for the previous example would be written as
<link rel=“canonical” href =>.

This tag is a long overdue tool for fine-tuning the natural search performance of a Web site, and cleaning up search indexes in general. More information about the canonical tag, its importance and smart ways to use it can be found in 360i’s latest POV on “Canonical Tags & Duplicate URLs.”

POVs are delivered regularly to 360i’s clients. If you’re interested in viewing this or other reports, or for more information, please contact us at