Topic summary
Grammars

Extracted from the Wikipedia article Grammar.
Development
Grammars evolve through usage. Historically, with the advent of written representations, formal rules about language usage tend to appear also, although such rules tend to describe writing conventions more accurately than conventions of speech. Formal grammars are codifications of usage which are developed by repeated documentation and observation over time. As rules are established and developed, the prescriptive concept of grammatical correctness can arise. This often produces a discrepancy between contemporary usage and that which has been accepted, over time, as being standard or "correct". Linguists tend to view prescriptive grammar as having little justification beyond their authors' aesthetic tastes, although style guides may give useful advice about standard language employment based on descriptions of usage in contemporary writings of the same language. Linguistic prescriptions also form part of the explanation for variation in speech, particularly variation in the speech of an individual speaker (for example, why some speakers say "I didn't do nothing", some say "I didn't do anything", and some say one or the other depending on social context).