Grammar

:This article is about grammar from a linguistic perspective. For English grammar rules, see English grammar.

Types of grammar

• A prescriptive grammar is a grammar that asserts itself as the only correct formulation of a particular language, and rejects any other constructions as wrong. Traditional grammars are typically prescriptive. Prescriptive grammars are usually based on the prestige dialects of a speech community, and often specifically condemn certain constructions which are common only among lower socioeconomic groups, such as the use of "ain't" and double negatives in English. Though prescriptive grammars remain quite common in pedagogy and foreign language instruction, they have fallen out of favor in modern academic linguistics, as they represent only a limited subset of how people actually use a language.
• A descriptive grammar is a grammar that describes the language as it is actually used by people, regardless of whether prescriptive grammars would consider a construction correct or not. Descriptive grammars are bound to a particular speech community, and attempt to provide rules for any utterance considered grammatically correct within that community. For example, in many dialects of English, the use of double negatives is very common, even though prescriptive English grammars explicitly reject double negatives as ungrammatical. A descriptive grammar of a speech community where people acceptably say "I didn't do nothing" will treat that sentence as grammatical, and provide rules that account for it. A descriptive grammar of formal English would rather provide rules for "I didn't do anything."
• Traditional grammar is the collection of ideas about grammar that Western societies have received from Greek and Roman sources. Prescriptive grammar is always formulated in terms of the descriptive concepts inherited from traditional grammar. Modern descriptive grammar aims to correct the errors of traditional grammar, and generalize them, so as to avoid shoehorning all languages to the model of Latin. Nearly all materials used in teaching language, however, are still based on traditional grammar.
• A formal grammar is a precisely defined grammar, typically used for computer programming languages.
• A generative grammar is a formal grammar that can in some sense "generate" the well-formed expressions of a natural language. An entire branch of linguistic theory is based on generative grammars. Generative grammars were popularized by Noam Chomsky.