DUOL

Duolingo, Inc.

A maker of free, game-like apps that teach dozens of languages — plus math, music, and even chess — through bite-sized lessons, streaks, and rewards. It was founded in 2011 by computer scientist Luis von Ahn and his Ph.D. student Severin Hacker at Carnegie Mellon University, after they noticed millions wanted to learn a language but couldn't afford pricey courses. The name blends the Latin "duo" (two) with "lingo" (language), and its green owl mascot Duo became famous for guilt-tripping users with persistent reminder notifications.