To say that linguistics is a descriptive science means that linguists tried to discover and record the rules to which the members of a language-community actually conform and does not seek to impose upon them other rules, or norms, of correctness. Prescriptive linguistics aims to lay down rules for the correct use of language and settle the disputes over usage once and for all. Descriptive approach to language attempts to tell what is in the language, while prescriptive approach to language tells people what should be in the language.

For example, “Don't say X” is a prescriptive command; “People don't say X” is a descriptive statement. The distinction lies in prescribing how things ought to be and describing how things are. In the 18th century, all the main European languages were studied prescriptively. However, modern linguistics is mostly descriptive because the nature of linguistics as a science determines its preoccupation with description instead of prescription.