The story behind “Inside Facebook” by JP Mangalindan @FortuneMagazine March 1, 2012, 10:09 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons FORTUNE — In eight years, the social network Mark Zuckerberg began coding in his Harvard dorm room has become a cyber institution with some 843 million users. Now, as Facebook readies to go public later this year, it is about to undergo the most dramatic change in its short history. Once it is public, Zuckerberg’s venture will almost certainly have the capital necessary to realize its biggest ambitions. But the riches of an IPO also threaten the uniquely bare-knuckle, scrappy culture the company has struggled to build. That is the subject of “Inside Facebook,” a feature appearing in the next issue of Fortune. In it, my colleagues Miguel Helft and Jessi Hempel dive into how the company has thrived and the dangers it faces ahead. Primary among its challenges are two divergent cultures, the one faithful to Zuckerberg’s hacker credo and the other shaped by COO Sheryl Sandberg’s more corporate tendencies. Among the revelations in the story: On Sheryl Sandberg and the circle of friends she has brought into the company: “There’s a term spoken quietly around Facebook to describe a cadre of elites who have assumed powerful positions under the leadership of Zuckerberg’s chief operating officer: They’re FOSS, or friends of Sheryl Sandberg. Many have followed her there after studying with her at the Harvard Business School or working with her at the U.S. Treasury Department or Google GOOG . Several middle and senior executives who have left the company say that Sandberg has put friends in powerful positions, sometimes even when they were less qualified than other Facebook employees, and once there they enjoy special status. ‘You can’t really cross a FOSS,’ says one former senior manager.” The mandatory six-week Bootcamp for engineers came about after a run in between engineers in the cafeteria: “After a quick orientation, bootcampers are given a computer and a desk. When they open their laptop the first time, they’ll often find six e-mails. One welcomes them to the company; the other five describe tasks they’re supposed to perform, including fixing bugs on the Facebook site. The goals are manifold. One is to get new employees comfortable with the idea that they have the power to push changes directly onto the Facebook site.” More than one-third of engineers transfer to other teams within the company. The ubiquitous, seemingly simple “Like” button underwent “dozens” of iterations. For more, read Helft and Hempel’s story here or purchase it from Amazon here or from Barnes & Noble here. You can also read it with the iPad app for free if you are a Fortune subscriber, or in the March 19 issue on newsstands.