If you think about companies that were built in Silicon Valley, a lot of them early on were chip companies. And now the companies that are there, like Apple, are much more successful than any of the chip companies were.

Find that thing you are super passionate about. A lot of founding principles of Facebook are that if people have access to more information and are more connected, it will make the world better; people will have more understanding, more empathy. That’s the guiding principle for me. On hard days, I really just step back, and that’s the thing that keeps me going.

My friends are people who like building cool stuff. We always have this joke about people who want to just start companies without making something valuable. There's a lot of that in Silicon Valley.

There are a few other things that I built when I was at Harvard that were kind of smaller versions of Facebook. One such program was this program called Match. People could enter the different courses that they were taking, and see what other courses would be correlated with the courses they are taking.

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.

I hope that Facebook and other Internet technologies were able to help people, just like we hope that we help them communicate and organize and do whatever they want to every single day, but I don't pretend that if Facebook didn't exist, that this wouldn't even be possible. Of course, it would have.

I think video is a mega trend, almost as big as mobile.