Mark Zuckerberg
CEO and co-founder of Facebook
Founded: May 2004

"Facebook's mission is to give people the power to share and make the world more open and connected."
--Mark Zuckerberg

One might assume that information would abound on the founder of a high-profile, multi-billion-dollar social networking site. Wrong. Information on Mark Zuckerberg is surprisingly scarce. Maybe that's just because the 24-year-old Harvard dropout has only ever held one job: CEO of Facebook.

Zuckerberg grew up in the New York City suburb of Dobbs Ferry, N.Y., and attended the Phillips Exeter Academy in New Hampshire. His father is a dentist, his mother a psychiatrist, and he has three sisters. He taught himself how to program computers, and during his senior year in high school, he and fellow hacker-programmer Adam D'Angelo caught the interest of AOL and Microsoft by creating a Winamp plug-in that could build customized playlists.

But both turned down job offers in order to attend college in 2002--Zuckerberg to Harvard and D'Angelo to CalTech. But Zuckerberg's undergraduate career in computer science wasn't destined to last. Not content to just study programming, he created a photo-rating site called Facemash, using photographs of other Harvard students from the school's online facebook (a yearbook-like publication designed to introduce students to one another). But he created his program by hacking into student records and using photos without permission, and was reprimanded by the administration for violating privacy rules and breaching computer security.

Zuckerberg, however, wasn't deterred. He eventually finished the platform for "The Facebook" (sometimes at the expense of attending class), combining the concept of traditional facebooks with large-scale social networking sites like Myspace and Friendster.

In February 2004, Zuckerberg launched the program from his dorm room with co-founders Dustin Moskovitz, Chris Hughes and Eduardo Saverin. In just a few weeks, more than half the school had opened accounts. The group quickly expanded to more universities and colleges, and that summer, Zuckerberg and his team moved to Palo Alto, Calif., renting a sublet and hooking up with investors like PayPal co-founder Peter Thiel and Napster co-founder Sean Parker.

By August 2005, Zuckerberg had officially changed the company's name to Facebook, and after raising $12.7 million in venture capital, was ready to move the company to the next level.

The site gradually expanded from college networks to include high school and work groups, and in September 2006, anyone with an e-mail address was allowed to join. Today, there are more than 110 million active users, and according to comScore Media Metrix, which tracks Web activity, Facebook rates as the Web's top photo-sharing site, and is the fourth most-visited site in the world, accounting for more than 1 percent of all internet use.

Of course, Zuckerberg's success hasn't been without some controversy. Some of his college peers have accused him of stealing the code for Facebook, and that court case is still pending. He also caused a media furor when he introduced the Newsfeed function, which shared all activity updates between people in their respective social networks--at first without a privacy option.

In response, Zuckerberg said in a New York Times article that "Facebook has always tried to push the envelope. And at times that means stretching people and getting them to be comfortable with things they aren't yet comfortable with. A lot of this is just social norms catching up with what technology is capable of."

Regardless, the tech titans took notice. In 2006, Zuckerberg astonished the world by turning down Yahoo's offer to buy Facebook for $1 billion. A year later, Microsoft purchased a 1.6 percent stake in the company for $240 million.

No one except Zuckerberg probably knows where the company is going, but even he has said that the site is a "work in progress." Recently, though, prominent Google executives have made a career move to Facebook, which implies the company will be going seriously corporate--and soon, maybe public. But one thing is for sure: Zuckerberg will be a major player in the tech industry for years to come.

And in case you're wondering, you can't friend Zuckerberg on Facebook. That function's been disabled.