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 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.

The world is changing so quickly, with mobile stuff and different platforms emerging, that I think it's more likely that the biggest competitor for Facebook is someone that we haven't heard of. What that means for us is that we should just really stay focused on what we're doing.

I know it sounds corny, but I’d love to improve people’s lives, especially socially… Making the world more open is not an overnight thing. It’s a ten-to-fifteen-year thing.

The US government should be the champion for the internet, not a threat. They need to be much more transparent about what they're doing, or otherwise people will believe the worst.

If you live in an area where there is not a good school, the internet may be the best way to get access to a lot of education material. The same is true if there is not a good doctor - the internet may be the best way to get access to health.

While we generally believe in free speech and giving everyone as much ability to speak as possible, in practice there are lots of barriers to that, whether it's legal restrictions, technological restrictions or you can't share what you want if you don't have access to the internet.