Facebook, the most popular social networking Web site in the world, was founded in a Harvard dorm room in the winter of 2004. Like Microsoft, that other famous technology company started by a Harvard dropout, Facebook was not particularly original. A quarter-century earlier, Bill Gates, asked by IBM to provide the basic programming for its new personal computer, simply bought a program from another company and renamed it. Mark Zuckerberg, the primary founder of Facebook, who dropped out of college six months after starting the site, took most of his ideas from existing social networks such as Friendster and MySpace. But while Microsoft could as easily have originated at MIT or Caltech, it was no accident that Facebook came from Harvard.

What is “social networking”? For all the vagueness of the term, which now seems to encompass everything we do with other people online, it is usually associated with three basic activities: the creation of a personal Web page, or “profile,” that will serve as a surrogate home for the self; a trip to a kind of virtual agora, where, along with amusedly studying passersby, you can take a stroll through the ghost town of acquaintanceships past, looking up every person who’s crossed your path and whose name you can remember; and finally, a chance to remove the digital barrier and reveal yourself to the unsuspecting subjects of your gaze by, as we have learned to put it with the Internet’s peculiar eagerness for deforming our language, “friending” them, i.e., requesting that you be connected online in some way.

Facebook was successful early on because it didn’t depart significantly from how its audience interacted, and because it started at the top of the social hierarchy. Zuckerberg distinguished his site through one innovation: Facebook, initially at least, would be limited to Harvard. The site thus extended one of the primary conceits of education at an elite university: that everyone on campus is, if not a friend, then a potential friend, one already vetted by the authorities. Most previous social networks, such as MySpace and Friendster, had been dogged by the sense that, while one might use them with friends, they were to a substantial degree designed for meeting strangers. But nobody is a stranger in college, or at least that’s the assumption at a school like Harvard, so nobody would be a stranger on Facebook.

The site’s connection to collegiate social codes could be seen most clearly in its name, which, unlike that of every previous social network—Friendster and MySpace, but also SixDegrees, Bebo, Orkut, etc.—actually came from a preexisting, even highly traditional item, the freshman “facebook” that many colleges distribute to incoming students, with a photo of each classmate and a few identifying details. Zuckerberg’s Web site would retain the exclusivity of its namesake through one…