Marissa Mayer is the President and CEO of Yahoo!. Before taking the reins at Yahoo!, she spent most of her career at Google, going from one of its early engineers to Vice President of Local, Maps, and Location Services. A self-described “proud geek,” she holds a B.S. in symbolic engineering (studying interactions between human and artificial intelligences) and an M.S. in computer science, both from Stanford. In 1999, she joined a fledgling Silicon Valley startup as one of the company’s first twenty employees and its first female engineer. Mayer was a key player in the design of Google’s era-defining homepage; her logic and design sense are now woven into the daily lives of people at every corner of the globe. In her years heading Google's search business, she helped expand usage from a few hundred thousand searches per day to over a billion.