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Content is King, but Duplicate Content is a Royal Pain.

painkiller.jpgDuplicate content is one of the most common causes of concern among webmasters. We work hard to provide original and useful content, and all it takes is a malicious SERP (Search Engine Results Page) hijacker to copy our content and use it for his or her own. Not nice.

More troubling still is the way that Google handles the issue. In my previous post about cgi hijacking, was clear that the main problem with hijacking and content scraping is that search engines do not reliably determine who is the owner of the content and, therefore, which page should stay in the index. When faced with multiple pages that have exactly the same or nearly the same content, Google's filters flag them as duplicates. Google's usual course of action is that only one of the pages — the one with the higher PageRank — makes it to the index. The rest are tossed out. Unless there is enough evidence to show that the owner or owners are trying to do something manipulative, there is no need to worry about penalties.

Recently, regular reader Jez asked me a thought-provoking question. I'm paraphrasing here, but essentially he wanted to know: "Why doesn’t Google consider the age of the content to determine the original author?” I responded that the task is not as trivial as it may seem at first, and I promised a more thorough explanation. Here it is. Read more

Preventing duplicate content issues via robots.txt and .htaccess

Rand of SEOmoz.org posted an interesting article on duplicate content issues. He uses the typical blog to show different examples.

In a blog, every post can appear in the home page, pagination, archives, feeds, etc.

Rand suggests the use of the meta robots tag “no-index”, or the potentially risky use of cloaking, to redirect the robots to the original source.

Joost the Valk recommends WordPress users change some lines in the source code to address these problems.

There are a few items I would like to add to the problem and to the proposed solution.

As willcritchlow asks, there is also the problem of multiple URLs leading to the same content (ie.: www.site.com, site.com, site.com/index.html, etc.). This can be fixed by using HTTP redirects and by telling Google what is our preferred domain via webmaster central.

Reader roadies, recalls reading about a robots.txt and .htaccess solution somewhere. That gave me the inspiration to write this post.

After carefully reviewing Google’s official response to the duplicate content issue, it occurred to me that the problem might not be as bad as we think.

What does Google do about it?
During our crawling and when serving search results, we try hard to index and show pages with distinct information. This filtering means, for instance, that if your site has articles in “regular” and “printer” versions and neither set is blocked in robots.txt or via a noindex meta tag, we’ll choose one version to list. In the rare cases in which we perceive that duplicate content may be shown with intent to manipulate our rankings and deceive our users, we’ll also make appropriate adjustments in the indexing and ranking of the sites involved. However, we prefer to focus on filtering — rather than ranking adjustments … so in the vast majority of cases, the worst thing that’ll befall webmasters is to see the “less desired” version of a page shown in our index.

Basically, Google says that unless we are trying to do something purposely ill intended (like ‘borrowing’ content from other sites), they will only toss out duplicate pages. They explain that their algorithm automatically detects the ‘right’ page and uses that to return results.

The problem is that we might not want Google to choose the ‘right’ page for us. Maybe they are choosing the printer-friendly page and we want them to choose the page that includes our sponsors’ ads! That is one of the main reasons, in my opinion, to address the duplicate content issue. Another thing is that those tossed out pages will likely end up in the infamous supplemental index. Nobody wants them there :-).

One important addition to Rand’s article is the use of robots.txt to address the issue. One advantage, this has over the use of the meta robots tag “no-index”, is in the case of RSS feeds. Web robots index them, they contain duplicate content but the meta tag is intended for HTML/XHTML content and the feeds are XML content.

If you read my post on John Chow’s robots.txt file, you probably noticed that some of the changes he did to his file, were precisely to address duplicate content issues.

Now, let me explain how you can address duplicate content via robots.txt. Read more