Why is there a need for a clear language policy?

The preservation of cultural and linguistic diversity in today's world is a major concern to many scientists, artists, writers, politicians, and leaders of linguistic communities. Up to one half of the 6000 languages currently spoken in the world are estimated to be in danger of disappearing during the 21st century. Many factors affect the existence and usage of any given human language, including the size of the native speaking population, its use in formal communication, and the geographical dispersion and the socio-economic weight of its speakers. National language policies can either mitigate or exacerbate the effects of some of these factors.