Google Inc (NASDAQ:GOOG) punishes websites that try to trick the system to get higher search rankings and more traffic. Recently, the search engine giant penalized Rap Genius for using shady SEO tactics. The hip-hop startup later made amends with Google to end the punishment. Companies like Overstock.com, Inc. (NASDAQ:OSTK) and J.C. Penney Company, Inc. (NYSE:JCP) have also been caught in the past for using unscrupulous tactics to boost their search rankings.

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But why did Google Inc (NASDAQ:GOOG) level the hammer at the travel website? Expedia Inc (NASDAQ:EXPE)’s visibility in Google search results dipped more than 25% between January 12-19, according to Searchmetrics. As a result, Expedia shares plunged 4% on Tuesday. Searchmetrics Founder Marcus Tober told USA Today that Expedia was either participating in paid link-building schemes, or it has been a victim of “negative SEO.”

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Three possible reasons Google punished Expedia

Tober said the Bellevue-based travel agency’s SEO techniques are so outdated and clumsy that Expedia Inc (NASDAQ:EXPE) alone might not be responsible for the scheme. He cites three possibilities that could have potentially prompted Google Inc (NASDAQ:GOOG) to take stern action against its techniques. One, Expedia might have adopted paid link-building technique years ago and forgot it, so links remained on the web. Two, maybe some of the company’s departments or a third-party hired by Expedia is still using the technique. Expedia is a big company with multiple departments. So, it’s likely that one of its departments is still using the paid linking technique.

Third, one of its competitors built such links over a long time in the past to hurt Expedia Inc (NASDAQ:EXPE). This strategy is called “negative SEO.” Google Inc (NASDAQ:GOOG) continuously improves its search algorithm to yield most relevant results to users and filter out spam. And if a website breaks its rules, the Mountain View-based company manually deflates its rankings.

Expedia violates Google’s rules

Google Inc (NASDAQ:GOOG) has long advised companies not to pay publishers to include links to their relevant web pages. But there are thousands of web pages and blogs where terms like “hotels,” “United Airlines,” “Car rental” and “guaranteed best price on airfare” are linked to the relevant pages of Expedia Inc (NASDAQ:EXPE)’s website. Tober said most businesses stopped using this technique more than 10 years ago. So, why would Expedia still do this? That’s why Searchmetrics thinks that it may have been caused by negative SEO.

Google Inc (NASDAQ:GOOG) has reiterated that publishing useful and relevant connect is the best thing for SEO.