A descriptivist approach deals with describing language as it exists. It involves cataloguing all kinds of language use, from the young and the old, the rich and the poor, urban and rural, formal and informal, etc.
A prescriptivist approach deals with norms and standards. It lays down a set of rules that delineate the standard version of a language.
Both approaches are important, IMO. And they are not necessarily in conflict. In the ideal world, a descriptivist understands that a legal contract must be precise, and that the language used is extremely important. Also, in the ideal world, a prescriptivist understands that the language used in court is not exactly the same language used in pubs.
Pope of the Dictionary.com Forum
Thank you for your explaination
if you are a teacher of EFL what approach you will use to teach your learner?
please have me some more idea