Grammar is the sound, structure, and meaning system of language. All languages have grammar, and each language has its own grammar. People who speak the same language are able to communicate because they intuitively know the grammar system of that language—that is, the rules of making meaning. Students who are native speakers of English already know English grammar. They recognize the sounds of English
words, the meanings of those words, and the different ways of putting words together to make meaningful sentences.
However, while students may be effective speakers of English, they need guidance to become effective writers. They need to learn how to transfer their knowledge of grammatical concepts from oral language to written language.
We are all born with the neurological wiring, or capacity, to learn language, and infants spend a good portion of their first two years
learning the structure of the language--or languages--they hear spoken around them. This is a complex--and marvelous--process that we
all went through, and it is learning that takes place unconsciously; in other words it does not require formal instruction. Do you ever
see toddlers memorizing lists of irregular verbs? By the time a child is ready to enter kindergarten, she already "knows" in the unconscious sense just about all of the linguistic structure she will need to make sense in her native language(s).But anyway we have to polish our unconscious sense through learning grammar so that we become a good speaker.