Marissa Mayer, one of the most well-known and longest-tenured employees of Google, resigned from Google today. She will take over as CEO of Yahoo tomorrow, the New York Times and other outlets are reporting.

The struggles of Yahoo are well documented. The company lost the search market to Google many years ago, and things became worse in May when then-CEO Scott Thompson was forced out of the company because he lied about having a computer science degree. The 37-year-old Mayer—who is an engineer, Google's twentieth employee, and one of the most powerful women in the technology industry—will try to bring some much-needed stability to her former rival.

Mayer was vice president of search products and user experience at Google between 2005 and 2010. Most recently, she was vice president of local, maps, and location services. Mayer also serves on Walmart's board of directors and will join the Yahoo board in addition to serving as CEO.

Mayer is a major talent, but one person alone won't be able to bring Yahoo back to its former glory. When asked for his opinion, Gartner analyst Michael Gartenberg told us, "As my grandfather said, 'The cemeteries are full of people that could be replaced.' I suspect Google will get along fine. The question is what can Ms. Mayer do that others have been unable to? Certainly Yahoo has the market attention with this talent at the helm, but it's only the execution that will matter."

Mayer confirmed the move on Twitter. In Yahoo's official announcement she was lauded for having "managed some of Google's most successful innovations, launching more than 100 features and products including image, book and product search, toolbar, iGoogle, Google News, and Gmail—creating much of the 'look and feel' of the Google user experience."

Mayer called Yahoo "one of the Internet's premier destinations for more than 700 million users," and said, "I look forward to working with the company's dedicated employees to bring innovative products, content, and personalized experiences to users and advertisers all around the world."

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