The Harvard dormitory where Facebook was born is a red brick and ivy-draped campus castle that, beyond just being a place to sleep and study, has long prided itself as a community of the best and the brightest.

But Kirkland House - where a curly-haired 19-year-old prodigy named Mark Zuckerberg hid out in his room for a week writing the computer code that would eventually redefine the way people interact on the Internet - is wary of threats to its sanctuary. "Do not copy or lend your key to anyone," it instructs residents. "Do not allow anyone access to the House unless you know him/her."

Ever since Zuckerberg dropped out at the end of his sophomore year, he has worked to create an online world where such rules no longer apply.

Facebook - with 500 million users, the world's largest social networking site - began as a tool for communication between people who knew each other and were bound by shared and exclusive interests. Zuckerberg required those signing up to have a Harvard e-mail address, months after the university nearly expelled him for hacking its computers and jolting the campus with a site that encouraged students to rank their classmates' looks.

That site, called Facemash, made fast enemies. But with its successor, Zuckerberg vastly expanded what it means to make friends.

Zuckerberg, now 26, has built Facebook into an international phenomenon by stretching the lines of social convention and embracing a new and far more permeable definition of community. In this new world, users are able, with a few keystrokes, to construct a social network well beyond what would ever be possible face-to-face. We are encouraged to disclose personal information freely, offering up the stuff of everyday life as material worthy of the biggest stage. In Zuckerberg's world, the greatest status is conferred on those who "friend" others fast and frequently, even those they've never met.

"I'm trying to make the world a more open place," Zuckerberg says in the "bio" line of his own Facebook page.

This week, ready or not, the publicity-shy wunderkind - whose own story has largely escaped the public's attention despite widespread fascination with the network he created - is being forced into the open in a way far beyond his control.

On Friday, Hollywood laid out its version of his story in a movie called "The Social Network." The script by Aaron Sorkin ("The West Wing") depicts Zuckerberg as a socially inept and intellectually corrupt genius, fighting wars with both friends and rivals for the right to call Facebook his own.

The movie comes a week after Zuckerberg, in the last chance to shape his image independently, appeared on the Oprah Winfrey show to announce a $100 million donation to the long-troubled Newark, N.J., school system, casting himself as the nation's brightest young face of philanthropy.

"When you look at the gift to Newark what it demonstrates is his recognizing that he can't leave it to the movie to define his image to the general public because he has no image," said David Kirkpatrick, author of "The Facebook Effect," a book chronicling Zuckerberg's story that was written with the cooperation of the man and his company.

Central to this tale: the contradiction between the blank slate that is Zuckerberg, and his campaign to get people to bare their souls via Facebook.

A Facebook spokesman, Larry Yu, said Zuckerberg would not agree to an interview to talk about himself. That reluctance, he acknowledges, contributes to the vacuum that is the CEO's public persona.

"He is a shy guy, no question about it," Yu said. "He does not like doing press stuff. What excites him is building things."

Yu said Zuckerberg was not trying to seize control of his image with the donation to Newark. Company public relations staff had warned him to delay the announcement because it would be seen as a ploy, he said. Zuckerberg decided to go ahead despite that concern, because the timing suited city and state officials and the producers of "Oprah," Yu said.

Zuckerberg, who grew up in the New York suburb of Dobbs Ferry, N.Y., in a hilltop house where his father still runs a first-floor dental practice, was a programming prodigy. He began writing code at 10 on an Atari computer his dad bought, devising games and having friends do the graphics. As a senior at Phillips Exeter Academy, he and a friend created a web tool called Synapse that built personalized music playlists by automatically determining listener's preferences. Microsoft reportedly offered the pair nearly $1 million, but they turned it down.

Exactly what happened after he got to Harvard in 2003 depends on who's doing the recounting. Soon after he arrived, Zuckerberg created a site called Coursematch that allowed students to choose classes by showing what their classmates were doing. Then, in the fall of his sophomore year, he hacked into the online "facebooks" of Harvard's residential halls to create Fashmash.

"The Kirkland facebook is open on my computer desktop and some of these people have pretty horrendous facebook pics. I almost want to put some of these faces next to pictures of farm animals and have people vote on which is more attractive," Zuckerberg wrote at the time, in his online journal.

The university's Administrative Board called him in for a hearing, but let him remain at the school. Zuckerberg told the Harvard Crimson student newspaper that criticism of the site had made him rethink its viability.

"Issues about violating people's privacy don't seem to be surmountable," he said in an e-mail to the Crimson. "I'm not willing to risk insulting anyone."

In early 2004, former classmates say, the normally sociable Zuckerberg all but vanished for a week, emerging from his room to urge his friends to join a new creation called The Facebook.