Whatever the world's current linguistic diversity, it is steadily declining, as local forms of speech increasingly retreat before the advance of the major languages of world civilization. ‘The future of languages‘ compares linguistic and biological extinction. Languages ‘reproduce‘ by transmission from current speakers to new generations, so a language's survival depends on the extent to which new generations are learning it. Critical factors are the number of speakers, their proportion in the community, areas where it is spoken, government policies and attitudes towards its use. Language extinction involves loss of knowledge of the natural world, loss of history and heritage and lost opportunities to understand the nature of language.