Linguists tend to focus on natural languages, like English, German, Arabic or Japanese.
And quite honestly, I’m not an exception to that. But I do have a history with and fascination for constructed languages (popularly called “conlangs”). Of course, one reason to invent a language is simply to entertain its creator. But the most intriguing reason is to enable groups of people who may speak completely different languages to communicate.
Today, English often serves the role of such a lingua franca internationally (and that’s at least part of the reason why this blog is written in English). This is not without its problems: the communication does not take place on a level playing field, because native speakers in the Anglo-American world have an obvious advantage (although I’ve been told that my English is not too far off). Besides, there is a definite tendency to overrate English proficiency around the world: I’ve travelled extensively enough in Europe to know that there are a great many people who barely speak the language, if at all. You can also use an online writing service for successful learning and correct writing on foreign language.
I remember being especially intrigued at the age of 11 when I discovered the most successful of the invented languages, Esperanto. With a simple and completely regular grammar (which can be summed up in 16 rules), a small basic vocabulary which can be expanded indefinitely with the help of affixes (for example, “granda” means “big”, and if you add the prefix “mal-” you automatically get a word with the opposite meaning “small”, malgranda), and even a fair amount of literature, it has managed to gain some momentum over the years.
Since those days, my enthusiasm has cooled off somewhat and I have become more cynical. I doubt whether any language, whether it is natural or constructed, could really fill the role of a global lingua franca properly.
So at the end of the day, I prefer to learn a new language so I can speak with people directly. There is nothing that compares to it.