The field of language ecology studies the interrelationships between speakers and their languages as situated in their full (contemporary and historical) context. In its strong version, a theory of language ecology likens competition between languages to the competition between species and provides mechanisms for accounting for the survival of the fittest (languages). Language planning should take into account the overall language ecology of any group, which can be seen as a framework or model for analysing the relationship between linguistic practices on the context, or milieu, in which they are situated, that is, their ecolinguistic niche. Most linguists would argue that it is possible to place language vitality along a continuum, with languages which are vital and in no way endangered (e.g. English, Mandarin, and Spanish) on one end, and extinct languages which have no speakers and have vanished without descendent or daughter languages on the other end.