When you think about it, there's no way to input things into a computer. It's all... the holes only go out, right? Like you can plug a keyboard or a mouse in but that's a trick because the computer thinks the inputs are outputs. That's a programmer trick, basically magic. The key to the future is to make holes that go in too.

I mean, we've built a lot of products that we think are good, and will help people share photos and share videos and write messages to each other. But it's really all about how people are spreading Facebook around the world in all these different countries. And that's what's so amazing about the scale that it's at today.

Building a mission and building a business go hand-in-hand. It is true that the primary thing that makes me excited about what we're doing is the mission, but I also think, from the very beginning, we've had this healthy understanding which is that we need to do both.

Facebook is inherently viral.

We've changed our internal motto from "Move fast and break things" to "Move fast with stable infrastructure."

I started the site when I was 19. I didn't know much about business back then.

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