Duolingo may be notorious for its persistent, aggressive, even passive-aggressive practice reminders. But, it seems, some of that nagging could have been better served to Duolingo itself. This summer it’s finally making good on its new year’s resolution – five years late.

This month, Duolingo finally launched its long-awaited course in Arabic for English speakers, after being delayed several times.

With more than 300 million users, Duolingo is the largest online language platform in the world, with more people learning a second language through its smartphone apps than in public schools in the United States. But many users have long wondered why Duolingo taught fictional languages such as Star Trek’s Klingon and Game of Thrones’s High Valyrian, but not the planet’s fifth-most popular language – Arabic.

Duolingo first hinted at an Arabic course in 2014 – so why the delay?

“There were various starts and stops – Arabic is a very difficult language to learn, as well as teach, and we wanted to get it right,” Michaela Kron, a spokesperson for Duolingo, tells The National.

Requests for an Arabic course peaked during the European migration crisis of 2015, when courses were launched for Arabic ­asylum-seekers learning German, French and Swedish, a Duolingo spokesperson says. An Arabic course for English speakers had been delayed dozens of times since Duolingo first hinted it was coming soon, back in 2014. At the time the company had called for contributors to its Arabic course when it launched the incubator programme.

Duolingo’s Incubator model relies on unpaid volunteers to contribute and translate the content taught using its app, which is free to use. But even after the final phase of beta development got fully up and running in January, it stalled again, and the projected release date had to be pushed back to March, which it then again delayed to July.

Interest in the new Arabic course has been high, though – more than 300,000 users have registered in the first two weeks, the spokesperson says.

Interest in learning Arabic is now higher than ever

According to a study by the Pew Research Centre, Arabic is now the fastest-growing language in the United States. The Arab American Institute estimates more than 3.7 million Americans can trace their ancestry back to an Arab country.

So why has it taken so long for Duolingo’s Arabic course to finally catch up with demand? Anyone who has ever tried to learn Arabic knows it’s an incredibly rich and complex language. Even after mastering its scriptand learning to read from right to left, students have been eternally confounded by the realisation that Arabic is, in fact, not actually a single language. It exhibits a unique quality known as “diglossia” – meaning that it’s actually two languages in one. An Arabic speaker has to speak two distinct, yet parallel languages that co-exist side by side with different domains of use.

It’s a tricky language, and there are many forms to learn

The written form, known as Modern Standard Arabic, is usually learnt in school from age six, and is used for reading, writing and formal situations. The native language, on the other hand, which people most commonly use to express themselves in everyday situations, is a local or regional dialect of Arabic. Varying widely across the Arab world these dialects can be so different they’re as distinct as Spanish is to Portuguese.

“Arab people often find themselves code-switching between Standard Arabic and their own native dialect depending on the situation,” says Nizar Habash, a professor of computational linguists at NYU Abu Dhabiwho also specialises in using artificial intelligence to analyse the evolution of spoken Arabic dialects for the university.

I think of this not as a fragmentation, but rather a richness, that makes Arabic a very colourful language, and very alive

– Nizar Habash, NYU Abu Dhabi

In theory, Modern Standard Arabic is understood as a lingua franca by all Arabic speakers, since when written, it is always the same. But because of diglossia, it functions only as the written form of the language, making it sound as erudite as Shakespeare when spoken. “People never actually use [Modern Standard Arabic] in their everyday speech,” says Habash. “It’s not actually owned by anybody, and nowhere in the world is anyone actually a native speaker of it.”

For centuries, the two sides of the Arabic coin has remained mostly in its own spheres: formal, written Arabic remaining only for writing and reading,with localised dialects for speaking. “When people write or communicate in a dialect, they’re expressing a very rich culture that is close to their heart and that they grew up with,” says Habash.

Arabic has been constantly evolving and adapting for centuries, and today’s generation have added their own spin of innovation. Because the internet is both an informal space, but one where people communicate by writing, it presents a unique evolution that the language has never encountered. With smartphones, the relationship between informal, chatty Arabic and formal written forms has become more complicated, giving rise to a hybrid known as “Arabeezy” – or Arabic written with Latin characters and numbers to represent letters that have no English equivalent. To make things even more complicated there is no standardisation of the many different dialects of Arabic, which can even vary from city to city in the same country – much like accents and vernacular change from London to the North of England to Scotland.

For its Arabic course, Duolingo has chosen to teach Modern Standard with a mix of regional dialects, and it also includes Arabeezy (or rather, 3rabeezy) to ease the learning curve. “There’s this bias, and it’s very unfortunate that it exists,” says Kron. “Everyone has their own reasons for learning a language – it could be for travel, for relocating, for doing business with the Arab world, or if you have an Arabic-speaking neighbour you want to make them feel welcome in your community. We want to bring the world closer together through language.”

There are few resources for learning Arabic, so Duolingo does fill a gap, but the material doesn’t go beyond beginner level. Advanced learners may find more of a challenge in Mango Languages, another online service that teaches four different dialects of Arabic, including Modern Standard.

Any app that aims to teach Arabic ultimately faces the same issue. The question of what is the “correct” version of a dialect – and who gets to decide that – is a politically loaded one. There’s no single, centralised institution such as the Academie Francaise for French, which can give an official ruling on the language – so there is no single, monolithic Arabic. Dictionaries are only beginning to codify dialects that were for centuries only spoken and never written.

“I think of this not as a fragmentation,” says Habash, “but rather a richness, that makes Arabic a very colourful language, and very alive.”