All of my friends who have younger siblings who are going to college or high school - my number one piece of advice is: You should learn how to program.

Berlin is one of my favorite cities in the world. I feel like the energy is very youthful. It has such an important history, including its recent history of unification.

In the olden times, privacy was good. Today people want to share, people are more open.

A guy who makes a new chair doesn't owe money to everyone who ever built a chair.

It used to be the case, like, you'd switch jobs, and then maybe you wouldn't keep in touch with all the people that you knew from that old job. Just because it was too hard. But one of the things that Facebook does is it makes it really easy to just stay in touch with all these people.

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

It is important for young entrepreneurs to be adequately self-aware to know what they do not know.