Advertising works most effectively when it's in line with what people are already trying to do. And people are trying to communicate in a certain way on Facebook - they share information with their friends, they learn about what their friends are doing - so there's really a whole new opportunity for a new type of advertising model within that.

Facebook is uniquely positioned to answer questions that people have, like, what sushi restaurants have my friends gone to in New York lately and liked? These are queries you could potentially do with Facebook that you couldn't do with anything else, we just have to do it.

Facebook is inherently viral. There are lots of sites that include a contact importer, and for lots of them it doesn't really make sense. For Facebook it fits so well. It wasn't until a few years in that we started building some tools that made it easier to import friends to the site. That was a huge thing that spiked growth.

There have been misperceptions that we're trying to make all the information open on Facebook, and that's completely false. There are big buckets of information that we recommend that you share with only your friends privately. Then some of the more basic information, we recommend that that's visible to everyone.

Facebook is shaping a broader web. If you look back for the past five or seven years, the story about social networking has really been about getting people connected. But if you look forward for the next five years, I think that the story people are going to remember five years from now isn't how this one site was built; it is how every single service that you use is now going to be better with your friends.

We're a community of a billion-plus people, and the best-selling phones - apart from the iPhone - can sell 10, 20 million. If we did build a phone, we'd only reach 1 or 2 percent of our users. That doesn't do anything awesome for us. We wanted to turn as many phones as possible into 'Facebook phones.' That's what Facebook Home is.