Of course, it's finger language

Esperanto is the only one that comes to mind.

I am very much in favor of a system under which each person would grow up learning his national language, and also a world language.  Under such a system the cultural diversity and richness of the world's language pool would be preserved, and at the same time, all peoples, from wherever they're from, would be able to communicate on the level of native speakers of the world language.  The choice of the world language could prove contentious, so in order to avoid any possible national jealousies, the world language very well could be an artificial tongue, such as Esperanto.

You mean artificial language.You know it dpesn't work.As far as I remember it was Esperanto.

Well, some years ago Latim was the universal language.