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

In a recent survive of Millennials around the world asking what most defines our identity, the most popular wasn't nationality, ethnicity or religion. It was "citizen of the world." That's a big deal. Every generation expands the circle of people we consider one of us. And in our generation, that now includes the whole world. This is the struggle of our time. The forces of freedom, openness, and global community against the forces of authoritarianism, isolationism, and nationalism - forces for the flow of knowledge, trade, and immigration, against those who would slow them down.

There are many machines throughout history that were built to do something better than a human can.

I actually do think you're seeing this trend towards organizations just caring more about their brand and engaging. And so I think Home Depot will want to humanize itself. I think that's a lot of why companies are starting blogs, are just giving more insight into what's going on with them.

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.

Why are most chess masters under 30?

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.