One common way to divide the different types of English Grammars available is to label them descriptive or prescriptive, though a grammar may contain elements of both.
The principles around which they are written are very different; a prescriptive grammar is one that lays down the rules for English language usage, while a descriptive grammar synthesises rules for English usage from the language that people actually use. A prescriptive grammarian believes that certain form used are correct and that others, even though they may be used by native speakers, are incorrect. Many prescriptivists feel that Morden linguistics, which tends to place emphasis on actual rather than perceived language usage, is responsible for decline in the standard of language. Descriptivists look at the way people speak and then try to create rules that account for the language usage, accepting alternative forms that are used regionally and also being open to forms used in speech that traditional grammars would describe as errors.