Young people are just smarter.

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

It only took me two weeks to build the first version of Facebook because I had so much stuff before then.

If you live in an area where there is not a good school, the internet may be the best way to get access to a lot of education material. The same is true if there is not a good doctor - the internet may be the best way to get access to health.

When I'm introspective about the last few years I think the biggest mistake that we made, as a company, is betting too much on HTML5 as opposed to native... because it just wasn't there. And it's not that HTML5 is bad. I'm actually, on long-term, really excited about it. One of the things that's interesting is we actually have more people on a daily basis using mobile Web Facebook than we have using our iOS or Android apps combined. So mobile Web is a big thing for us.

You can be so bad at so many things... and as long as you stay focused on how you're providing value to your users and customers, and you have something that is unique and valuable... you get through all that stuff.

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.