German-Guatemalan Luis von Ahn is the person who makes us prove we’re not robots online with his CAPTCHA code. Von Ahn, a computer scientist born in Guatemala, co-invented CAPTCHA. Its full title is the long-winded Completely Automated Public Turing test for telling Computers and Humans Apart. He is why internet browsers often have to click a box to prove they are not bots. Von Ahn is the co-founder of the language-learning website Duolingo. He also works as a consultant professor at Carnegie Mellon University.