Luis is an inventor and computer science professor at Carnegie Mellon. He is one of the creators of CAPTCHA, a system that allows websites to determine whether you’re a human or a computer. CAPTCHAs are wavy, distorted words that people need to type out when they’re submitting a form to a website. Luis’ company ReCAPTCHA proved users were humans while also digitizing books. The company was sold to Google in 2009. He also founded the language learning app Duolingo, attracting over 150 million users in its first four years. Luis won a Macarthur Genius Grant in 2006. Luis speaks with Jessica Harris about how he launched ReCaptcha and Duolingo, from scratch. Listen to the interview