Way back in November of 2011, Duolingo opened up their private beta and was hit with a flood of excitement in the form of invite requests. “People asking me for Duolingo invites: Patience, grasshoppers,” said creator Luis von Ahn. For …

Duolingo’s premise is quite simple. How do you get people to translate the web for free? Their answer is to turn it into an experience that is part game, part language instruction, and all ambitious crowdsourcing. Duolingo is the brainchild …