Facebook is really about communicating and telling stories... We think that people can really help spread awareness of organ donation and that they want to participate in this to their friends. And that can be a big part of helping solve the crisis that's out there.

Today we can only hear the voices and witness the imaginations of one-third of the world's people. We are all being robbed of the creativity and potential of the two-thirds of the world not yet online. Tomorrow, if we succeed, the Internet will truly represent everyone.

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.

In a lot of ways Berlin is a symbol for me of Facebook's mission: bringing people together, connecting people and breaking down boundaries.

The trick isn't adding stuff, it's taking away.

It took 10 years to go from building the initial Smartphone to reaching the mass market. BlackBerry came out in 2003 and it didn't get to about a billion units until 2013. So I can't imagine it would be much faster for VR.

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.