Friends, soulmates, lost parents, not to mention work opportunities — for about 10 percent of the planet, Facebook is where you go to find much of what matters most in life.
Think of Facebook as something like a 24-hour party, virtual of course, with a chance to meet your friends' friends. Instead of spotting someone across the room, you'll first see them in their profile picture. You might not hear them telling a funny story to a group in the corner of the room, but you could easily be enticed by the comments they put up on their page or that of other people.
The virtual party can lead to real love, as it did for Sandrine, who lived in Italy and met Antoine who lived in Paris, but, like her, was on Facebook. Today they have a flesh-and-blood little daughter.
"We were both playing on a Facebook game app and ended up fighting against a common friend," Sandrine recalled. "It started with silly exchanges like, 'don't touch him, leave him to me!' Then it went to little messages, then long mails, and finally a highly emotional meeting two months later."
This global address book, with more than 800 million active members, may also allow you to search for lost friends or even close relatives. It's cheaper and easier than going to a private detective, at least.
Caner Ongun, a 44-year-old Turkish man living in New York, had lost all trace of his friend Cetin for 15 years. He knew that he had moved to Veracruz in Mexico, but neither Internet searches, nor telephone listings helped track him down.
When Ongun signed up to Facebook in 2007, it took him only a few clicks before he found Cetin was also on the network.
Cetin had left Turkey after divorcing. He was a sailor and spent long months without communicating with his ex-wife and daughter, who had moved and couldn't themselves get in touch with him. They had come to believe the worst had happened.
"I wrote my daughter's name on Google and saw her as a user of Facebook, but I didn't know what is Facebook," Cetin said. Since then, he's been back in almost daily contact with his estranged daughter, even if they haven't met for real.
Amy, a U.S. woman, recounted how she found her high school best friend after along separation.
"She was my best girlfriend, but we went to different universities, etc. We hadn't spoken for about 20 years, and I found her on Facebook. Turns out, she was living near my mom in North Carolina all this time. We have spent a lot of time together over the last couple of years and now we are celebrating her 40th birthday."
In an increasingly globalized world, Facebook is proving an ideal tool.
Stephen Todd, a consultant for fashion magazine Supply, said that of his 1,053 friends on Facebook, only 99 are at home in Sydney.
"What Facebook does most for me is allow me to feel close to friends all around the world, no matter how incisive or banal... the exchange."
For those wanting jobs or other commercial endeavors, not friends, Facebook is also a sort of worldwide advertising billboard.
Whether you're an artist, journalist or jewelry maker, your Facebook page is now a first stop for fans, customers, and co-workers.
Stephanie Chayet, a French journalist in New York and a master of the ironic "status" update on her page, wrote this summer: "Sorrel — the new spinach."
Before she knew it, her Facebook-trawling editors had commissioned an article on "the latest culinary fads."
Her sister Camille, meanwhile, got an internship after discovering an offer on Facebook, her yoga instructor-friend used the network to find her first clients — the list goes on.
Then there's Gilles Verdiani, a French scriptwriter. His "status" updates made between 2009 and 2010 on becoming a new father didn't just attract attention online: They'll be coming back out in May in France as an old-fashioned book.