Before you question the niche appeal – or even absurdity – of language learning platform DuoLingo offering a course in Klingon for passionate Trekkies, it is worth noting it already offers High Valerian, one of the fictional languages of Westeros in television series Game of Thrones. There's even an opportunity to learn Dothraki at fan site Dothraki.irg.
Klingon, however, unlike these Johnny-come-latelys, was fully developed as a written and spoken language back in the early 1980s by American linguist Marc Okrand while working on Star Trek II: Wrath of Khan. Okrand has written several books based on the language including a Klingon dictionary.
DuoLingo has been working on this course for over two years and finally, if you take enough lessons, you can claim full fluency in Klingon because: not yap wa’ Hol! (one language is never enough!).