prescriptivism/descriptivism

The prescriptivist approach to language favours rules that identify a traditionally 'correct' use of language usage.
They disapprove of uses of language that break these certain rules.

The 18th century is when they were established;efforts to standardise the language were later developed.(e.g books of grammar).The aims of this approach could be to establish a standard language, to teach and construct what a particular society perceives is correct language, or to advise on effective communication. If usage preferences are conservative,prescription might appear resistant to a language change.

Prescriptivist approaches to language are mainly concerned with how the 'prescriptivist' recommends language should be used,or what is thought of as being the linguistically correct use of that particular language. This has a direct contrast with the approach of descriptive linguistics, which observes how language is actually used.

Descriptivist approach, or descriptive linguistics bears reference to the way language is actually spoken,rather than how people think it should be spoke,and seek to do this as accurately and objectively as possible. Linguistic description is frequently linked with linguistic prescription,which is most commonly found in education and publishing.
 Prescription seeks to define standard language forms and give advice on effective language. It is seen by and thought of by many as a presentation of descriptive language in its most learnable form, even though it grasps onto on more subjective aspects of language.Prescription and description are complementary, but have different priorities which evidently come into conflict. 
Descriptive is more considerate to language adaptation and change, and that it is more important to teach,study and practice, whereas prescriptivism is less considerate and more stubborn, not showing any attitudes that have changed from socially acceptable/ 'correct' language usage.