More than 1.4 billion people around the world use Facebook today, thanks to founder and CEO Mark Zuckerberg.
Connecting that many people — and, of course, selling them ads — has made Zuckerberg and his company quite a bit of cash.
The Harvard dropout’s current net worth is about $US33.4 billion, putting him at No. 16 in Forbes’s ranking of the world’s billionaires.
Here’s a closer look at his simultaneously down-to-earth and yet extravagant life.
(Former Business Insider reporter Rebecca Borison wrote an earlier version of this post)
Edward and Karen Zuckerberg, a dentist and a psychiatrist respectively, raised four children: Randi, Donna, Arielle, and, of course, Mark, in Dobbs Ferry, New York. A precocious child, Mark created a messaging program called 'Zucknet' using Atari BASIC at age 12. As a kid he also coded computer games for his friends.
While attending high school at the renowned Phillips Exeter Academy in New Hampshire, he built an early music streaming platform, which both AOL and Microsoft showed interest in. Still a teen, he rejected offers for an acquisition or a job.
He wasn't just a computer nerd though. Zuck loved the classics -- 'The Odyssey' and the like -- and he became captain of his high school fencing team.
Soon after Zuckerberg started at Harvard University in 2002, he earned a reputation as a skilled developer. He started 'The Facebook' with several friends out of his dorm room and dropped out of school after his sophomore year to focus on it full-time.
Before dropping out, Zuckerberg met his now-wife, Priscilla Chan. Chan told 'Today's' Savannah Guthrie that they met at a frat party. 'On our first date, he told me that he'd rather go on a date with me than finish his take-home midterm,' she said.
The company raised its Series A -- $12.7 million -- when Zuckerberg was barely legal drinking age. The rest is history. In 2010 he was named Time Magazine's 'Person of the Year.'
Not many tech CEOs get to see themselves immortalised on the big screen, but in 2010, 'The Social Network' put a dramatized version of Facebook's founding story in theatres. It earned eight Academy Award nominations but Zuckerberg strongly maintains that many of its details are incorrect.
Aaron Sorkin directed 'The Social Network.' Zuck may have hated the movie, but Sorkin's hit TV show 'The West Wing,' is one of his favourites.
Zuckerberg took the company public on May 18, 2012. The IPO raised $16 billion, making it the biggest tech IPO in history until Alibaba won the spot late last year.
Chan and Zuckerberg continued to date throughout Facebook's rise to greatness and the lovebirds finally got married the day after the company went public. The relatively low-key event was actually a 'surprise' wedding: Guests thought they were celebrating a med school graduation party for Chan. They tied the knot at their Palo Alto home.
The two honeymooned in Italy, flying in on a private jet and staying at a five-star hotel, Portrait Suites, where rooms start at €800 per night. But paparazzi also spotted the couple eating in McDonald's while overseas.
The couple tends to set aside two weeks every December to travel, sometimes visiting Chan's family in China.
Zuckerberg studies Chinese, and his Mandarin was so good by fall 2014 that he managed to hold a 30-minute Q&A in the language.
They have an adorable Hungarian sheepdog named Beast who looks like a tail-wagging mop and even has his own Facebook page.
Occasionally selling Facebook stock keeps Zuckerberg so rich he doesn't need a salary: The CEO makes $1 a year. He did, however, require $610,454 in 2014 for catered, privately chartered jets for himself and his guests.
And he's far from flashy with his wealth. 'He's the poorest rich person I've ever seen in my life,' Tyler Winklevoss once said of Zuckerberg in an interview.
Instead of a Tesla or a Ferrari, Mark Zuckerberg drives a black Volkswagen GTI with a manual transmission, which costs around $30,415.
In October 2014, he shelled out $100 million for 750 acres of secluded land on Hawaiian island Kauai. He's using the land to build a private getaway.
In Palo Alto, Zuckerberg spent more than $45 million buying his 5,000-square-foot home and then all the other land and buildings around it.
He also bought a $10 million mansion in San Francisco, and then proceeded to spend more than $1 million on remodeling and additions (like a $60,000 greenhouse).
During the renovation, he allegedly hired people to sit in cars parked near the house at night to save parking spaces for the construction workers.
Besides privacy, Zuckerberg spends his money on trying to make the world a better place. He donated $992 million to the Silicon Valley Community Foundation in 2013 and $75 million to San Francisco General Hospital in 2014.
Zuck's been much looser with Facebook's money than his own, though: The company has some major acquisitions under its belt, including $1 billion for Instagram, $19 billion for WhatsApp, and $2 billion for Oculus.
But even Zuckerberg can't always get what he wants: He tried to buy Snapchat for $3 billion in 2013, but CEO Evan Spiegel turned him down.
Besides other tech celebrities, Zuck frequently meets with other important people like Brazil's president, Dilma Rousseff...
Slightly less glamorous: Earlier this year an New York graffiti artist debuted a Zuckerberg portrait made of faeces.
At 31, Zuckerberg is one of a very small, elite group who has more billions of dollars than he has years on earth.
But despite his billions, Zuck seems incredibly down-to-earth. He holds regular 'Townhall' style Q&A sessions where he chats with regular people from all over the world. Here's a shot from one that took place in May:
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