So many businesses get worried about looking like they might make a mistake, they become afraid to take any risk. Companies are set up so that people judge each other on failure. I am not going to get fired if we have a bad year. Or a bad five years. I don’t have to worry about making things look good if they’re not. I can actually set up the company to create value.

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.

At Facebook, we're inspired by technologies that have revolutionized how people spread and consume information. We often talk about inventions like the printing press and the television - by simply making communication more efficient, they led to a complete transformation of many important parts of society. They gave more people a voice. They encouraged progress. They changed the way society was organized. They brought us closer together.

People developed planes first and then took care of flight safety. If people were focused on safety first, no one would ever have built a plane.

Why are most chess masters under 30?

Having two identities for yourself is an example of a lack of integrity.

The companies that work are the ones that people really care about and have a vision for the world so do something you like.