I worked on a number of projects that were used by millions of people and that also served as inspiration to what we now call "crowd-sourcing."

In 2011, after spending a couple of years working at Google, I decided that I wanted to dedicate myself to helping to transform education. I was particularly inspired by my upbringing in Guatemala, a poor country where high-quality educational opportunities are limited to those who have money.

I co-founded Duolingo with the mission of bringing free language education to the world.

One fact we're particularly proud of is that there are more people learning languages on Duolingo in the US than there are people learning languages in the entire US public school system.

Before the Internet, coordinating more than 100,000 people, let alone paying them, was essentially impossible. But now with the Internet, I've just shown you a project where we've gotten 750 million people to help us digitize human knowledge.

I worked on a number of projects that were used by millions of people and that also served as inspiration to what we now call "crowd-sourcing."

Every time you buy tickets on Ticketmaster, you help to digitize a book.