Secret communication
If you and some of your relatives, friends or colleagues speak a language that few people understand, you can talk freely in public without fear of anyone eavesdropping, and/or you can keep any written material secret. Speakers of such Native American languages as Navajo, Choctaw and Cheyenne served as radio operators, know as Code Talkers, to keep communications secret during both World Wars. Welsh speakers played a similar role during the Bosnian War.