Duolingo is a service that aims to translate internet content into multiple languages, while teaching users foreign words and grammar. Created by reCAPTCHA’s Luis von Ahn and Severin Hacker, a Ph.D. student at Carnegie Mellon University, the platform launches today.

The premise behind the service is simple but ambitious. Learners choose what language they wish to study. Duolingo provides sentences, matched up to the learners’ skill level, and asks the users to translate them. If a word is too confusing, learners can roll over it for a list of potential translations.

Once a learner submits the translation, he will get a response from Duolingo’s feedback system that explains what he did wrong (or congratulates him on a job well done). A learner will also be able to read others’ translations to see how his peers translated the same sentence, learning the flexibility of the language (as von Ahn notes in this blog post, even simple sentences can be translated in hundreds of different ways). To strengthen a user’s weak areas, Duolingo will keep track of problem words and drill down on those in following lessons.

Part of Duolingo’s appeal for learners is the ability to work on ‘real’ text, rather than sentences out of a textbook. “When you’re doing the real-world stuff, you really feel like you’re accomplishing something. It reinforces why you’re working to understand this new language,” said von Ahn, who is also a professor at Carnegie Mellon. The ability to get feedback instantaneously — as one would from a teacher — is also important, as it draws learners in and lets them know the progression of their studies.

Currently, Duolingo offers free lessons in English, Spanish, German, and French. Italian, Chinese, and Portuguese are listed as coming ‘later.’ Given the popularity of English and Chinese on the internet, translating content into multiple languages could be immensely useful to millions across the world. According to von Ahn, 100,000 beta testers have already translated tens of millions of sentences, and about 500,000 more are lined up to take advantage of the free language instruction service when it opens up to the public tomorrow.

There are several hurdles facing Hacker and von Ahn. One that figures to be among the most difficult to bypass will be attracting advanced learners to translate the hardest texts. But if Duolingo is able to deliver on its bold promise and shake up not only the world of translation but also language learning, it may very well be a game-changer.

To learn more about the service, check out our feature Duolingo and the Power of Human Computation.