Mark Zuckerberg, the Harvard dropout who changed what it means to be social, cemented his Silicon Valley legend and cash riches Friday by leading Facebook to a historic Wall Street debut.

The hoodie-wearing 28-year-old, depicted in the Hollywood drama "The Social Network," as a socially challenged computer geek, has evolved into a confident chief executive presiding over an online community of more than 900 million.

Despite his massive wealth, Zuckerberg's look has not changed over the years, and he still favors t-shirts, jeans and sneakers, topped off by his trademark hooded sweatshirt and a mop of brown, curly hair.

Wearing a tie daily became one of the annual goals that Zuckerberg sets for himself as a way of expanding his life to include more than just work, though company insiders recount how hard it was to get him to give up wearing sandals.

In 2011, his aim was to become a vegetarian and "only eat meat if I kill the animal myself."

In 2010, his goal was to learn Chinese. "Some members of my girlfriend's family only speak Chinese and I wanted to be able to talk to them," he said.

Zuckerberg rang the Nasdaq opening bell remotely from Facebook's new campus in the northern California city of Menlo Park on Friday, marking the largest IPO ever by an Internet firm.

The $16 billion IPO is structured to keep control of Facebook in the hands of Zuckerberg, who has been Time's "Person of the Year" and cracked the Forbes list of 20 richest people in the world.

Born on May 14, 1984, Zuckerberg was raised in Dobbs Ferry outside New York, one of four children of a dentist father and a psychiatrist mother.

He began writing computer programs at the age of 11 including one said to resemble Pandora's musical taste program which reportedly drew the interest of AOL and Microsoft.

He went to high school at the prestigious Phillips Exeter Academy, where he was captain of the fencing team, before entering elite Harvard University.

Zuckerberg launched Thefacebook.com, as it was then known, from his dorm room on February 4, 2004 with roommates and classmates Dustin Moskovitz, Chris Hughes and Eduardo Saverin.

The stated goal: "Making the world more open and connected." Going public on Wall Street eight years later in some ways completes the journey.

Facebook's early years were not without controversy, however.

In 2008, a $65 million settlement was reached with three Harvard classmates -- twins Tyler and Cameron Winklevoss, and Divya Narendra -- over their charges that Zuckerberg had stolen the idea for Facebook from them.

The conflict was at the heart of "The Social Network," the Oscar-winning film written by Aaron Sorkin and directed by David Fincher.

Zuckerberg left Harvard in May 2004 for Silicon Valley, where he received his first major funding -- $500,000 -- from PayPal co-founder Peter Thiel followed by nearly $13 million the next year from Accel Partners.

Despite recurring privacy complaints, Facebook has gone from strength to strength, growing from 50 million members in 2007 to more than 900 million today with a billion users on the horizon.

Zuckerberg's Facebook page, which has attracted 13 million fans, contains pictures of his girlfriend, Priscilla Chan; his dog, Beast, and co-workers. His "likes" include the band "Linkin Park" and the documentary "Waiting for Superman."

Zuckerberg has been referred to by some as being struck in the mold of Apple co-founder Steve Jobs, who died last year of cancer. Zuckerberg has praised Jobs as a friend and a role model.

Similarities between the men include not being afraid to risk falling down while chasing big dreams, according to Creative Strategies principal analyst Tim Bajarin.

"He has the Silicon Valley DNA that you can't be afraid to fail," Bajarin said of Zuckerberg.

"Another thing that is very much Steve Jobs is he has a vision and he follows that vision no matter what anybody else says."