Sheryl Sandberg is an American technology executive, activist, and author best known as the chief operating officer (COO) of Facebook. She currently sits on Facebook's board of directors as its first female member. She is also the founder of Leanin.org and the co-author of two books, ‘Lean In: Women, Work, and the Will to Lead’ with Nell Scovell, and ‘Option B: Facing Adversity, Building Resilience and Finding Joy’ with Adam Grant. Before joining Facebook, she was the vice president of global online sales and operations at Google and helped launch its philanthropic arm Google.org. She also served as the chief of staff for United States Secretary of the Treasury Lawrence Summers, who was her professor at Harvard and her mentor. She has been invited as a keynote speaker at various events and delivered the TED speech titled “Why we have too few women leaders”. In 2012, she was named in the ‘Time 100’, ‘Time’ Magazine’s annual list of the 100 most influential people in the world, and currently ranks fourth on ‘Forbes’ list of most powerful women.