I think there's confusion around what the point of social networks is. A lot of different companies characterized as social networks have different goals - some serve the function of business networking, some are media portals. What we're trying to do is just make it really efficient for people to communicate, get information and share information.

More than four million businesses have Pages on Facebook that they use to have a dialogue with their customers.

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.

You can use your real identity, or you can use phone numbers for something like WhatsApp, and pseudonyms for something like Instagram. But in any of those you're not just sharing and consuming content, you are also building relationships with people and building an understanding of people.

We started off as this platform inside Facebook; and we were pretty clear from the beginning that that wasn't where it was going to end up. A lot of people saw it and asked, 'Why is Facebook trying to get all these applications inside Facebook when the web is clearly the platform?' And we actually agreed with that.

What we will do is we'll say, 'Okay, you have your page, and if you're not trying to organize harm against someone, or attacking someone, then you can put up that content on your page, even if people might disagree with it or find it offensive.' But that doesn't mean that we have a responsibility to make it widely distributed in News Feed.