When Mark Zuckerberg launched Facebook in his cramped Harvard dorm room in 2004, it was just one of the college sophomore's many online social experiments.
An earlier one, called Course Match, helped Harvard undergraduates see the courses their classmates were taking. Yet another, FaceMash, which gave Zuckerberg one of his first tastes of controversy, let students vote for the hottest kids on campus.
A talented programmer sometimes willing to dodge rules for information, Zuckerberg, 26, marshaled several of his projects to some level of success. But with Facebook, he hit it out of the park.
From a three-man operation fueled by Red Bull and beer, Facebook has grown into the world's largest social network. The company is on the verge of surpassing 500 million members and employs more than 1,400 people.
But though the story of Facebook, and the improbable adolescent who founded it, is impressive, it isn't without its complications. A rebellious, young CEO, mountains of personal information and an unbending vision to make the world more open can mean a bumpy path to success.
In his book, "The Facebook Effect," which is released today, technology journalist David Kirkpatrick chronicled the story of Facebook, from its creation to its controversies to its power to connect the world.
He is a longtime senior technology editor for Fortune magazine who interviewed Zuckerberg for the first time just as Facebook was taking off.
Kirkpatrick spoke with ABCNews.com Friday about Facebook, its privacy issues, its impact and its CEO. Below is an edited version of the conversation.
Why did you think that now was the time to write a book on Facebook?
"[It has an] impact on a variety of arenas of human activity, politics, marketing, media, our sense of our own identity, to some extent, personal behavior. What's really incredible to me is that Facebook, which is really, in many ways, a fundamentally new form of human communication, has been adopted now by 500 million people and is rapidly growing probably toward a billion and maybe beyond.
"And when you have such a huge proportion of humanity, and such a large percentage of people in our own country, and many other countries, using a new means of communication that has all these very powerful aspects to it, I think it's just really an exiting thing to write about."
Zuckerberg was 19 years old when launched Facebook, now he's 26 years old. Obviously, times change. How much has Zuckerberg changed since 2004?
"At his talk at [the All Things Digital conference last week], if you saw the videos he was really painfully recalling or having to fend off questions of when he was a 19-year-old college student. I think he started Facebook as just a kind of lark really, because he could, because he was a brilliant programmer and he had a good idea and he kind of thought it might be fun for his friends and he treated it very casually at the time.
"As he's gained more and more employees, he's reached [about] 1,500 of them, his own sense of responsibility has grown and there's no question he's not the same person he was when he was 19. ...
"Hopefully, we've grown some between 19 and 26 and I think he has in all the normal ways, except he's done it very much in public with an extraordinary, growing set of responsibilities. I think, in general, he's done a pretty good job of growing into his responsibility."