Today, it is estimated about 2 million people have some understanding of Esperanto. In the past, it was hoped the language would become a reasonable alternative to English or French as a truly global language.
Friday marks 100 years since the death of Ludwik Lejzer Zamenhof, the creator of Esperanto. Advocates once hoped the designed language would become used around the world as an easier-to-learn alternative to English.
But the language has been largely forgotten and only practised by small groups around the world.
Sam Cowie has more from Rio de Janeiro.