What's the best way to learn a new language? Or perhaps I should say: Quelle est le best way to pick up une lingua nouveau?

The age-old advice has been to move abroad and immerse yourself for at least a year. That didn't stop language schools like Berlitz from popping up as, perhaps, adjuncts to the crappy language instruction we received in high school Spanish and French classes. And before Rosetta Stone there was that creepy and bizarre cartoon VHS series Muzzy. Now the playing field is cramped with apps, websites, and books all claiming to offer the proper tools for language mastery.

Then there's Duolingo, a Pittsburgh-based company launched in 2011 that offers a free language learning app. Today, the company is announcing a $20 million Series C round of funding led by Kleiner Perkins Caufield & Byers, with the intent of becoming the most ubiquitous language acquisition program around.

The program is the brainchild of Carnegie Mellon computer scientists Luis von Ahn. He is quite an impressive figure unto himself. Beyond being a computer science professor at one of the best universities in the country, he is a MacArthur Grant recipient, as well as the brains behind CAPTCHA human verification program and its sibling reCAPTCHA. The reCAPTCHA program, which was bought by Google, simultaneous allows people to prove to web services they are human while crowdsourcing this action to digitize information -- such as words in books. That is, while you're filling out a CAPTCHA form, you are additionally helping digitize archives.

Von Ahn has fine-tuned the Duolingo software to collect and utilize data by the user to tailor to help each user learn best. As Hamish McKenzie explained last year:

Duolingo pays attention to which questions you struggle with, which ones you fly through, and what sorts of mistakes you make. It then aggregates that data with the vast swathes of other data is processes and learns from the patterns it sees. That information informs which questions it delivers to you, and at what times. In other words, it is constantly, dynamically tailoring your lessons so that you are being challenged in the most relevant ways.

Its business plan is similarly innovative. Von Ahn has coded into Duolingo's software the ability to perform translation services for external companies. So while users are learning languages they are also, unknowingly, performing simultaneous tasks to help translate documents. The company has signed translations deals with both CNN and Buzzfeed. More of these are on the horizon, von Ahn says.

The purpose of this fundraise, he says, is to make Duolingo the number one language learning program. "We're number one on Android, number one on iOS, number one on the web, but we're not the de facto way to learn language," he told me. This $20 million injection will be used to bolster the program to ensure more user acquisition, and thus become know as the predominate way to learn a foreign tongue. He is not hiring marketers, just more engineers. "It's really about improving the product to just continue getting better," he says.

Two new updates to be released shortly are a groups feature and language certification. The groups function would be predominately used by teachers so they could more easily track how a group of people are doing. In von Ahn's estimation, this would make Duolingo more accessible to larger institutional clients.

The certification, however, is perhaps the most interesting development. Duolingo wants to create a new standard by which people can prove to institutions and jobs that they know English. Now there are a few tests people can take that are widely accepted. The problem is they cost hundreds of dollars and require traveling to a proctored exam. Duolingo is developing a new app that will let people take the exam online, using the device's camera, but will be proctored. Because he needs to hire a proctoring service, he is charging a fee. It will only be $20, which is far less than the $200-$300 fee most other programs charge.

Von Ahn hopes that, at the very least, this new app will give other language certification tests a run for their money. "It's almost immoral to charge this for people who don't make that much money," he says. He points the the fact that many people who take these exams are living in developing nations where hundreds of dollars could mean days of wages. "At the very least, we'll get [the other tests] to lower their prices."

For Duolingo the question is no longer about its rise to success, but how successful and lasting it can be. The app counts more than 20 million users around the world, and was voted "App of the Year" by Apple in 2013, which is Apple's top honor chosen at the end of each year. Now it needs to gain new usership and keep the users it has. That is, it's time to see whether or not Duolingo is a wayward fad.

I have high hopes, and I think the certification test is a bold idea that could give it some sticking power -- at least for institutions that rely on these tests. So, too, is its monetization plan of selling translations. The next few years will show the kind of company Duolingo can become.

Will it go the route of Muzzy, or become something more useful and long-lasting? Here's hoping it's the latter.

[Image via Duolingo]