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Google penalizes duplicate content

January 17th, 2012 | Add a Comment

Duplicate content

Duplicate content generally refers to substantive blocks of content within or across domains that either completely match other content or are appreciably similar. Mostly, this is not deceptive in origin. Examples of non-malicious duplicate content could include:

Discussion forums that can generate both regular and stripped-down pages targeted at mobile devices
Store items shown or linked via multiple distinct URLs
Printer-only versions of web pages

If your site contains multiple pages with largely identical content, there are a number of ways you can indicate your preferred URL to Google. (This is called “canonicalization”.) More information about canonicalization.

However, in some cases, content is deliberately duplicated across domains in an attempt to manipulate search engine rankings or win more traffic. Deceptive practices like this can result in a poor user experience, when a visitor sees substantially the same content repeated within a set of search results.

Google tries hard to index and show pages with distinct information. This filtering means, for instance, that if your site has a “regular” and “printer” version of each article, and neither of these is blocked with a noindex meta tag, we’ll choose one of them to list. In the rare cases in which Google perceives 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. As a result, the ranking of the site may suffer, or the site might be removed entirely from the Google index, in which case it will no longer appear in search results.

There are some steps you can take to proactively address duplicate content issues, and ensure that visitors see the content you want them to.

Use 301s: If you’ve restructured your site, use 301 redirects (“RedirectPermanent”) in your .htaccess file to smartly redirect users, Googlebot, and other spiders. (In Apache, you can do this with an .htaccess file; in IIS, you can do this through the administrative console.)
Be consistent: Try to keep your internal linking consistent. For example, don’t link to http://www.example.com/page/ and http://www.example.com/page and http://www.example.com/page/index.htm.
Use top-level domains: To help us serve the most appropriate version of a document, use top-level domains whenever possible to handle country-specific content. We’re more likely to know that http://www.example.de contains Germany-focused content, for instance, than http://www.example.com/de or http://de.example.com.
Syndicate carefully: If you syndicate your content on other sites, Google will always show the version we think is most appropriate for users in each given search, which may or may not be the version you’d prefer. However, it is helpful to ensure that each site on which your content is syndicated includes a link back to your original article. You can also ask those who use your syndicated material to use the noindex meta tag to prevent search engines from indexing their version of the content.
Use Webmaster Tools to tell us how you prefer your site to be indexed: You can tell Google your preferred domain (for example, http://www.example.com or http://example.com).
Minimize boilerplate repetition: For instance, instead of including lengthy copyright text on the bottom of every page, include a very brief summary and then link to a page with more details. In addition, you can use the Parameter Handling tool to specify how you would like Google to treat URL parameters.
Avoid publishing stubs: Users don’t like seeing “empty” pages, so avoid placeholders where possible. For example, don’t publish pages for which you don’t yet have real content. If you do create placeholder pages, use the noindex meta tag to block these pages from being indexed.
Understand your content management system: Make sure you’re familiar with how content is displayed on your web site. Blogs, forums, and related systems often show the same content in multiple formats. For example, a blog entry may appear on the home page of a blog, in an archive page, and in a page of other entries with the same label.
Minimize similar content: If you have many pages that are similar, consider expanding each page or consolidating the pages into one. For instance, if you have a travel site with separate pages for two cities, but the same information on both pages, you could either merge the pages into one page about both cities or you could expand each page to contain unique content about each city.

Google no longer recommends blocking crawler access to duplicate content on your website, whether with a robots.txt file or other methods. If search engines can’t crawl pages with duplicate content, they can’t automatically detect that these URLs point to the same content and will therefore effectively have to treat them as separate, unique pages. A better solution is to allow search engines to crawl these URLs, but mark them as duplicates by using the rel="canonical" link element, the URL parameter handling tool, or 301 redirects. In cases where duplicate content leads to us crawling too much of your website, you can also adjust the crawl rate setting in Webmaster Tools.

Duplicate content on a site is not grounds for action on that site unless it appears that the intent of the duplicate content is to be deceptive and manipulate search engine results. If your site suffers from duplicate content issues, and you don’t follow the advice listed above, we do a good job of choosing a version of the content to show in our search results.

Duplicate content. There’s just something about it. We keep writing about it, and people keep asking about it. In particular, I still hear a lot of webmasters worrying about whether they may have a “duplicate content penalty.”

Let’s put this to bed once and for all, folks: There’s no such thing as a “duplicate content penalty.” At least, not in the way most people mean when they say that.

There are some penalties that are related to the idea of having the same content as another site—for example, if you’re scraping content from other sites and republishing it, or if you republish content without adding any additional value. These tactics are clearly outlined (and discouraged) in our Webmaster Guidelines:

Don’t create multiple pages, subdomains, or domains with substantially duplicate content.

Avoid… “cookie cutter” approaches such as affiliate programs with little or no original content.

If your site participates in an affiliate program, make sure that your site adds value. Provide unique and relevant content that gives users a reason to visit your site first.

(Note that while scraping content from others is discouraged, having others scrape you is a different story; check out this post if you’re worried about being scraped.)

But most site owners whom I hear worrying about duplicate content aren’t talking about scraping or domain farms; they’re talking about things like having multiple URLs on the same domain that point to the same content. Like www.example.com/skates.asp?color=black&brand=riedell and www.example.com/skates.asp?brand=riedell&color=black. Having this type of duplicate content on your site can potentially affect your site’s performance, but it doesn’t cause penalties. From our article on duplicate content:

Duplicate content on a site is not grounds for action on that site unless it appears that the intent of the duplicate content is to be deceptive and manipulate search engine results. If your site suffers from duplicate content issues, and you don’t follow the advice listed above, we do a good job of choosing a version of the content to show in our search results.

This type of non-malicious duplication is fairly common, especially since many CMSs don’t handle this well by default. So when people say that having this type of duplicate content can affect your site, it’s not because you’re likely to be penalized; it’s simply due to the way that web sites and search engines work.

Most search engines strive for a certain level of variety; they want to show you ten different results on a search results page, not ten different URLs that all have the same content. To this end, Google tries to filter out duplicate documents so that users experience less redundancy. You can find details in this blog post, which states:

When we detect duplicate content, such as through variations caused by URL parameters, we group the duplicate URLs into one cluster.

We select what we think is the “best” URL to represent the cluster in search results.

We then consolidate properties of the URLs in the cluster, such as link popularity, to the representative URL.

Here’s how this could affect you as a webmaster:

In step 2, Google’s idea of what the “best” URL is might not be the same as your idea. If you want to have control over whether www.example.com/skates.asp?color=black&brand=riedell or www.example.com/skates.asp?brand=riedell&color=black gets shown in our search results, you may want to take action to mitigate your duplication. One way of letting us know which URL you prefer is by including the preferred URL in your Sitemap.
In step 3, if we aren’t able to detect all the duplicates of a particular page, we won’t be able to consolidate all of their properties. This may dilute the strength of that content’s ranking signals by splitting them across multiple URLs.

Tool Check Duplicate Content ?