This article was taken from the May 2011 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by. It's a 120-million-member that's adding over 300,000 users a day, with more than 4. It has 's fastest-growing app, with 570,000 new daily users, making it the third-biggest app of all after and CityVille. Hugely profitable, it's forecast to generate hundreds of millions of dollars this year, and is being aggressively courted by venture-capital firms valuing it in the billions. And it's run from London by a secretive serial entrepreneur who has steadfastly refused to be interviewed or photographed. The world's largest social network is the world's largest social network that you probably haven't yet heard of. Run from 800-square-metre loft-style offices in Soho, it is brilliantly effective at providing one simple and universally compelling service: hooking up members according to their profile pictures and location. Relying on word-of-mouth rather than any marketing spend, it has cracked the internet's eternal conundrum: how to persuade users to pay hard cash in a world drowning in free digital services and content, by charging members each time they want to boost their visibility to others searching for a date. Today, A-list investors such as Sequoia and Accel are courting the business and there is talk of an initial public share offering. The basic mechanism of what Andrey has developed is genius -- just like with its AdWords, it's people paying for self-promotion. We were introduced in January by Israeli investor Yossi Vardi at Burda's DLD conference in Munich, which Vardi co-chairs, and later met in London. Vardi has no stake in Badoo. And then in mid-February, alone in an office belonging to Freud Communications, Andreev agreed to share his story. It has been a busy few days. Andreev explains that Michael Moritz, the legendary Sequoia investor who took early stakes in Google and , has just flown in from Palo Alto to meet him; he has also been meeting Kevin Comolli of Accel's London office. The secret sauces in companies like this are so nuanced, and the difference between getting it wrong and right lies only with these special people like Andrey. He's created something very powerful. Because it works, it grows like crazy. And people love it. We are like celebrities. In 2008, Andreev decided to test his assumptions of Spanish women and as an experiment refocused the site on meeting new people. At that time, France was growing fast, Italy was. Was it a attack or scammers? No, someone wrote an article about us. It's as if all the users jumped on the bus and went there. Bang -- in two months, suddenly we have a Turkish market with a million members. You could pay again to have your profile photo more widely visible across the site. He introduced virtual gifts to buy for your prospective date. If you want something to go faster, you pay. And some people pay tens of times every day to rise up. Or you can just walk past a nightclub and see who you can pick up before you get in. It's another opportunity to hook up random people for adventure. We're talking about real life, real time. We know this girl is 500 metres from here now. Within weeks, with barely any marketing, the iPhone app was the number-one social-networking app in France; after eight months, it had been downloaded 1. Andreev sees proximity as key to the business's future. Even desktop computer users can share their location by downloading an app that accesses Wi-Fi networks, IP addresses and other data points. We can also show the iPhone user that you're nearby. It was, he says, profitable in month two. He offered it as a white-label service to existing dating sites, letting them keep their ad revenue and deepening their subscribers' pool of prospective dates. Once it had a million members, a similar model emerged: a free site, it let users pay via premium to be more easily discovered. When you lose attention, like a Google search result, no one finds you. But people love advertising themselves. Lots of people use this function several times a day. Revenues climbed ever more steeply. You could send a gift, make a virtual phone call at 50 cents per minute. It was Mamba time. You can't imagine how cool it is to run things that are growing fast, getting revenue, watching the charts as the money grows -- it's a sport. After 18 months, Andreev had sold a fast-growing and highly profitable business, retaining no equity for himself. It was time to go global. If you try to learn something, you just get it. But with around 65 of its 120 staff, including its management and executive teams, based in Soho, this is effectively a British business. I feel at home here. I'm not sure I am able to give enough time. But I do play with Badoo, yeah. He pauses, then smiles. I think most of the guys and girls in the office are using it, they all have good experiences. And it helps them improve the features. And, yes, he is thinking about his next project. But it will be internet. The mobile internet is the biggest opportunity in the world. Smartphones outsold PCs last quarter. The opportunities will include meeting new people. Hook-up on mobile is a multibillion business. He shows his identity card: born in February 1974. They encouraged me to learn. It was not possible in Russia at that time to purchase anything from Europe, so it was a lot of fun to create something that could send 1kW of energy to the antenna on the roof. I spent years on this. He had saved money through the job and had time to think about what to do next. It helped webmasters track not only visits to their sites, but users' habits on the wider internet. Most webmasters were very happy to pay for this information. The business grew quickly -- the main Russian portals used it -- but 18 months later, he became restless. I was dreaming about advertising money. I knew you could make a lot from ads -- and if the market wants something that no one provides, you move. Google launched AdWords in 2000 but began keyword auctions in 2002. Soon, most keywords began to be very expensive. But he convinced Aport, then Mail. In month three, we returned everything that had been invested. We had a big success, so it was easy to speak to Rambler again. With money, you can speak with the big guys. It grew like crazy. I kept some guys running it. It was growing, it was good. Why not sell his stake? I just walked away. At the end of 2003, Finam acquired 80 percent of Begun. In terms of small experiments, of course -- some work, some don't. A week later we just removed it. Big companies spend months on marketing research. We go much faster -- prototype, build, see if it works, kill. In London, he does not own a car, but prefers to rent or. I'd love to stay here. Lucy, 19, told Wired she created an account after moving from Liverpool to London for university. My friend Josh said he uses Badoo to look for guys and that I should try it, so he came over armed with some alcohol and I signed up. I felt comfortable meeting up with him as it was in public, and he told me everywhere he was taking me. We've been on four dates and it's going well. Rafe, also from Madrid, has done just that. We talked for a month and one day he gave me his number. The next day he came to my house in the morning. Within an hour we were in my bed naked. Mary, 19, from London, says she joined to make new friends, and didn't anticipate being approached for sex. They are typically late 20s, 30s, even a 47-year-old. Some members are clearly there for professional sexual purposes. We have moderation, and when we see that happening, we delete those accounts. Controversy A network with Badoo's goals and scale naturally attracts controversy. And an evaluation of 45 social-networking sites by Joseph Bonneau and Sören Preibusch of Cambridge University gave Badoo the lowest score for. Is Andreev bothered by his site being accused, at the very least, of simply promoting promiscuity? If you go to a nightclub, of course you've got the opportunity to find a girl or a boy -- but it's not necessarily for sex, it could be to enjoy five mojitos and nothing else. Badoo is just a casual way to hook up with people, as you do in the street or nightclub. But we make the world work faster. Today Badoo is in 24 languages, and takes payment in 100 currencies, but the company eyes huge growth potential -- not least in markets such as the UK, where Swanson says there are 150,000 users. Badoo has barely got started on helping people hook up through their mobile devices. My challenge is to keep him here as long as possible. I need freedom, so I can build more things. I don't think I should be top 30, but top ten. I don't want that. You have something cool. This is mine -- I made it. It's like a kid. Before you have this, what's there to talk about? Additional reporting by Charlie Burton.