The thing I really care about is the mission, making the world open.

Our strategy is very horizontal. We're trying to build a social layer for everything. Basically we're trying to make it so that every app everywhere can be social whether it's on the web, or mobile, or other devices.

You grow more when you get more people's perspective.

People influence people. Nothing influences people more than a recommendation from a trusted friend. A trusted referral influences people more than the best broadcast message. A trusted referral is the Holy Grail of advertising.

On engagement, we're already seeing that mobile users are more likely to be daily active users than desktop users. They're more likely to use Facebook six or seven days of the week.

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.

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