At the age of 15 Heather Heldzingen first went to the Esperanto Club so she could run into Ivan, who she had a crush on.

Now she's teaching Esperanto to her and Ivan's grandchildren.

This July Mrs Heldzinger will travel to Buenos Aires for the 99th World Congress of Esperanto.

The 100th will be held in France next year.

Invented in the late 1870s and early 1880s to be a way to break down the language barrier, Esperanto continues to be spoken world-wide.

"It's a very special language, it's a beautiful language," Mrs Heldzinger told 774 ABC Melbourne's Richard Stubbs.

"You do feel energised with it simply because you know that you can speak to people all over the world."

Paco (peace)

Esperanto was created by Jewish ophthalmologist Ludwik Lazarus Zamenhof, who grew up in the city of Bialystok in what is now northeastern Poland.

In a now famous letter Zamenhof wrote how the city was divided into four ethnic groups: Russians, Poles, Germans and Jews.

Each group, he wrote, spoke their own language and looked upon the other ethnic groups as enemies.

"He thought, if I invent this language and we can all speak it there would be less wars, less disharmony," said Mrs Heldzingen.

Such a utopian vision was not shared by all.

Adolf Hitler wrote in Mein Kampf that Esperanto could aid the international Jewish conspiracy, while Joseph Stalin called it the "language of spies."

Both Hitler and Stalin banned the language and had Esperantists killed.

Ho Chi Minh, however, reportedly spoke Esperanto and was enthusiastic about its potential.

Amo (love)

Heather Heldzingen was 15 years old when she first came into contact with Esperanto.

"I met this beautiful young man who was wearing a green star," she said.

The man, who said his name was Ivan, told her the green star signified he could speak Esperanto.

Besotted, Heather went along to the Esperanto Club in Richmond in order to run into Ivan again.

The pair fell in love and were married for 50 years until Ivan passed away.

Mrs Heldzingen said she and her husband spoke Esperanto at home "mainly when the children were around and we didn't want them to know what we were talking about."

While her children never learned the language, she is now teaching her grandchildren - who love knowing a "secret" language their parents don't understand.

Komprenon (understanding)

The internet has been a boon to Esperanto, with several free courses available online.

"It's based on Latin roots but the inventor took parts of other different languages just to make it a wonderful, sublime language," said Mrs Mrs Heldzingen.

The language has changed little since it was created in the late 1870s and early 1880s.

The key to the language's continued success is how easy it is to learn.

"It's phonetic, you sound every letter," said Mrs Heldzingen. "There are only 16 simple grammar rules."

"Often we get people coming into our club who are quite fluent already."

These days the club meets once a week on Mondays at Ross House in Melbourne's CBD.