With almost one billion people using Facebook, The Economist's Robert Lane Greene visited the company's headquarters to learn what the social network is doing to real life.

One study of many on the phenomenon of "Facebook anxiety" produced a simple but striking finding: people's moods were depressed after reading their Facebook news feed, compared with a control group. One of the researchers attributed this to the fact that most status updates are positive. Reading an endless stream of mostly upbeat news from friends can cast your life in a bad light.

But that is far from fair to the full spectrum of life on Facebook. Life's hardships are lived socially too. There are groups for people with MS and HIV. A group brings together those with Asperger's Syndrome and their families. Characteristically, they share both problems and the neurological differences of which many "Aspies" are dead proud. Obsessions are compared -- baseball, cooking, dinosaurs, telephone boxes -- and commonalities unearthed: many Aspies, it turns out, love Lego, and creations are gleefully shared.

When a call for help goes out, Facebook becomes the world's biggest megaphone. I discovered this after hearing news of a rangy blond jock I'd played American football with in high school. Will was diagnosed with cancer in 2009, the year his first child was born; he was 34. Since then, the "Support Will Jones" public group on Facebook has racked up 1,500 members. Will has posted triumph, setback, triumph, setback and triumph. Around 900 people have offered him their prayers. When there has been good news, people have plied him with congratulations, which look heart-rendingly premature now. Two years later, Will is still alive, but tumours continue to reappear and require treatment. In "real" life, friends might have moved on or lost heart – it is crushingly hard to support someone with cancer over three years offline. But on Facebook 44 people cheered Will's latest piece of good news. If Facebook makes it too easy to express the vapid or insipid, it also allows us to go on benefiting from the far-flung relationships they might otherwise have let go cold.