Grammar is the set of rules and conventions that are the basis of the language.
Early English grammars were derived from the rules of Latin. The result was that they were over-rigid and even included ‘rules’ that did not apply to English at all. For example, there is no rule of English grammar that prohibits split infinitives, or prepositions to end sentences, or conjunctions to start them. These are matters of style not grammar.
In the 1960s English grammar was accused of restricting the personal development and free expression of young people. The previously accepted form of standard English was declared to be both a straitjacket on self-expression and a devious means of keeping ...