In linguistics, the grammar of a natural language is its set of structural rules on speakers' or writers' usage and creation of clauses, phrases, and words. The term can also refer to the study of such rules, a subject that includes phonology, morphology, and syntax, together with phonetics, semantics, and pragmatics. There are, broadly speaking, two different ways to study grammar: traditional grammar and theoretical grammar. Fluent speakers of a language variety or lect have internalised these rules. the vast majority of which – at least in the case of one's native language(s) – are acquired not by intentional study or instruction but by hearing other speakers. Much of this internalisation occurs during early childhood; learning a language later in life usually involves more direct instruction.The term "grammar" can also describe the linguistic behaviour of groups of speakers and writers rather than individuals. Differences in scale are important to this meaning: for example, the term "English grammar" could refer to the whole of English grammar (that is, to the grammar of all the language's speakers) in which case it covers lots of variation. At a smaller scale, it may refer only to what is shared among the grammars of all or most English speakers (such as subject–verb–object word order in simple sentences). At the smallest scale, this sense of "grammar" can describe the conventions of just one form of English that is better defined than others (such as standard English for a region). A description, study, or analysis of such rules may also be known as a grammar, or as a grammar book. A reference book describing the grammar of a language is called a "reference grammar" or simply "a grammar" (see History of English grammars). A fully revealed grammar, which describes the grammatical constructions of a particular speech type in great detail is called descriptive grammar. This kind of linguistic description contrasts with linguistic prescription, a plan to actively ban, or lessen the use of, some constructions while popularising and starting others, either absolutely or about a standard variety. For example, some pedants insist that sentences in English should not end with prepositions, a ban that has been traced to John Dryden (1631–1700). His unjustified rejection of the practice may have led other English speakers to avoid it and discourage its use. Yet ending sentences with a preposition has a long history in Germanic languages like English, where it is so widespread as to be the norm.Outside linguistics, the word grammar often has a different meaning. It may be used more widely to include rules of spelling and punctuation, which linguists would not typically consider as part of grammar but rather of orthography, the conventions used for writing a language. It may also be used more narrowly to refer to a set of prescriptive norms only, excluding the aspects of a language's grammar which do not change or are clearly acceptable (or not) without the need for discussions. Jeremy Butterfield claimed that, for non-linguists, "Grammar is often a generic way of referring to any aspect of English that people object to". Source: Wikipedia (en)