If a product costs $10,000 or $20,000 it has limited use. This is what the first computers cost! Only when almost everyone is able to afford it will it be a real thing.

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.

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.

There are a few other things that I built when I was at Harvard that were kind of smaller versions of Facebook.

In my experience everyone will have a different view of the right level of tax so governments need to provide clear guidance that conforms to a set of international standards that all governments accept.

At Facebook, we build tools to help people connect with the people they want and share what they want, and by doing this we are extending people's capacity to build and maintain relationships.

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