"Lean In: Women, Work, and the Will to Lead" is a book by Sheryl Sandberg, the Chief Operating Officer of Facebook. It explores the challenges women face in the workplace and encourages them to pursue leadership roles. Sandberg combines personal anecdotes with research to highlight the importance of women asserting themselves and overcoming societal barriers. The book also discusses the concept of "leaning in," which means actively engaging in one's career and seeking opportunities for advancement. Sandberg emphasizes the need for both women and organizations to foster an environment that supports female leadership and addresses gender inequality in the workplace.