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Recently we have started rolling out a series of algorithmic changes that aim to tackle hacked spam in our search results. A huge amount of legitimate sites are hacked by spammers and used to engage in abusive behavior, such as malware download, promotion of traffic to low quality sites, porn, and marketing of counterfeit goods or illegal pharmaceutical drugs, etc.

Website owners that don’t implement standard best practices for security can leave their websites vulnerable to being easily hacked. This can include government sites, universities, small business, company websites, restaurants, hobby organizations, conferences, etc. Spammers and cyber-criminals purposely seek out those sites and inject pages with malicious content in an attempt to gain rank and traffic in search engines.

We are aggressively targeting hacked spam in order to protect users and webmasters.

The algorithmic changes will eventually impact roughly 5% of queries, depending on the language. As we roll out the new algorithms, users might notice that for certain queries, only the most relevant results are shown, reducing the number of results shown:

This is due to the large amount of hacked spam being removed, and should improve in the near future. We are continuing tuning our systems to weed out the bad content while retaining the organic, legitimate results. If you have any questions about these changes, or want to give us feedback on these algorithms, feel free to drop by our Webmaster Help Forums.

Posted by Ning Song, Software Engineer