Zuckerberg took a graduate course in the subject at Mercy College near his home while still in high school.He enjoyed developing computer programs, especially communication tools and games.

I remember really vividly, you know, having pizza with my friends a day or two after—I opened up the first version of Facebook at the time I thought, "You know, someone needs to build a service like this for the world." But I just never thought that we'd be the ones to help do it.

And I think a lot of what it comes down to is we just cared more.

The group then introduced Facebook to other college campuses.

Facebook expanded rapidly, reaching one billion users by 2012.

Visitors to the site had to choose who was "hotter" and according to the votes there would be a ranking.

The site went up over a weekend, but by Monday morning, the college shut it down, because its popularity had overwhelmed one of Harvard's network switches and prevented students from accessing the Internet.

They'd come over, draw stuff, and I'd build a game out of it." However, notes Vargas, Zuckerberg was not a typical "geek-klutz", as he later became captain of his prep school fencing team and earned a classics diploma.

Napster co-founder Sean Parker, a close friend, notes that Zuckerberg was "really into Greek odysseys and all that stuff", recalling how he once quoted lines from the Roman epic poem Aeneid, by Virgil, during a Facebook product conference.

An earlier inspiration for Facebook may have come from Phillips Exeter Academy, the prep school from which Zuckerberg graduated in 2002.

It published its own student directory, "The Photo Address Book", which students referred to as "The Facebook".

According to writer Jose Antonio Vargas, "some kids played computer games.