For all his real-life social awkwardness , Mark Zuckerberg has been enamored with the intersection of software and social connections stretching back at least to his freshmen year at Harvard. One early application, called Coursematch, let students find out who else was enrolled in their classes. Another parsed the campus newspaper to locate people cited in its pages and link them through different articles.
His biggest splash came with Facemash, which chose for its inspiration Hot or Not, inviting students to upload pictures for peers to rate. Zuckerberg raided an online cache of Harvard student I.D. photos, posted them side by side, invited users to vote on whom was better looking and tabulated the results into a top-10 list for each campus house. Facemash proved popular and controversial, with the administration charging him with violating students' privacy. (He got off with a warning.) Then came thefacebook, his run in with the Winklevii , and the rest, as they say, is geek history.
While Zuckerberg prefers the word "iterate" to describe the bubbling change that has characterized Facebook  since its inception, there have been several pivots along the way. The first involved who could join the network. When Thefacebook.com debuted on the evening of Feb. 4, 2004, a Harvard email address was required for registration. Within 24 hours more than 1,200 students registered. Five days later the Harvard Crimson published a story on Thefacebook.com and by the end of the month three-quarters of the undergraduate population--about 7,000 students--had signed up.
Zuckerberg once told me he was amazed it took off so quickly. He had "a sense that the type of dynamics we were tapping into were pretty universal," but he was surprised his implementation “was so efficient at doing it." Soon other schools asked whether Thefacebook.com would launch outside of Harvard, and he spread it to Yale, Stanford, and Columbia.
Encouraged by the swift adoption, over the course of the semester he launched TheFacebook at 25 more schools. He and his roommates tacked up on their walls pictures of S-curves representing the adoption rates on various campuses. The bigger the school, the longer it took to arrive at full inflection. At Cornell a couple of weeks passed before exponential growth kicked in. As with smaller schools, however, eventually a critical mass was achieved; then there arose the social expectation that everyone had to be on it. Since students communicate with those attending other colleges there was significant pent-up demand for Thefacebook.com elsewhere, with campus newspapers trumpeting its arrival. This drove the site through the early signup phase, when the landscape was particularly barren and there was little utility for early adopters.
If Thefacebook.com had stayed within the safe confines of colleges it would have probably ended up a nice, niche business. But it expanded to high schools in September 2005 and then to big companies like Apple. It was this throwing open the doors to anyone that heralded Facebook’s rise as the largest social network on the planet.
There have been other pivots amidst all the iteration. The introduction of the Newsfeed, which quickly became the focal point for Facebook, is probably more of an iteration. Facebook’s transformation from a user-growth engine into a mature platform that other companies could base their businesses on was a pivot--a key one at that. And down the road Facebook’s mobile strategy could provide fodder for pivoting.
Picture, if you will, a Friday night in the near future--5, maybe 10 years from now. You head to a bar wearing your Google augmented reality glasses  (with the Prada frames) equipped with speech recognition software. You’re already logged into Facebook because that’s the default setting and who bothers to change this? You scan the room and because of Facebook’s vast facial recognition database--and the fact that almost everyone on the planet has a Facebook account—you are able to identify every person in the room, and how they relate to you and your social graph.
Is this a pivot or an iteration? I’m not sure, but whatever it is, it’s not far off. The real question is whether or not the location-aware integrated social network of the future will make future Mark Zuckerbergs, or anyone else, less socially awkward. Sarah Lacy, founder of PandoDaily , served up a deliciously insightful observation about the people behind Facebook, Twitter, indeed the entire web in an e-book  on the Facebook IPO that we worked on together. "The irony of the social media era," she wrote, is that "it was created by the world's least social people."
Adam L. Penenberg is a journalism professor at New York University. Follow him on Twitter: @penenberg