Duolingo

Teaching languages to the masses with a free app. Education may be the great equalizer, but access to it is hardly equal. That was what Luis von Ahn discovered growing up in Guatemala, where endemic poverty kept many from learning how to read or write. So von Ahn, a serial inventor and MacArthur "genius" grant recipient, teamed up with a fellow computer scientist at Carnegie Mellon to create Duolingo—a free, ad-supported app that makes it surprisingly easy to learn any of 36 languages on one's own in a short time. Lessons are intuitive, brisk, and game-like—which explains why 28 million people actively take its courses each month.