Grammar is the art of speaking and writing the language properly. Grammar teaches us how to use words in a proper manner. Grammar includes the general principles of a particular language. The established practice of the best speakers and writers of any language, is the standard of grammatical accuracy in the use of that language.
By the phrase, established practice, is implied reputable, national, and present usage. Usage becomes acceptable and legal, when it has been long and generally adopted.
Language and Stuff
The Importance of Grammar
English grammar is important to writers for several reasons. First of all, disregard of the correct use and combination of words is often considered a distinct mark of inferiority and a serious barrier to business and social advancement. A person's use of words is commonly taken as a measure of knowledge and even intelligence. Carelessness in this regard often causes a person to be held in much less esteem than one really deserves.
Divisions of Grammar—Definitions—Etymology.
In order to speak and write the English language correctly, it is imperative that the fundamental principles of the Grammar be mastered, for no matter how much we may read of the best authors, no matter how much we may associate with and imitate the best speakers, if we do not know the underlying principles of the correct formation of sentences and the relation of words to one another, we will be to a great extent like the parrot, that merely repeats what it hears without understanding the import of what is said. Of course the parrot, being a creature without reason, cannot comprehend; it can simply repeat what is said to it, and as it utters phrases and sentences of profanity with as much facility as those of virtue, so by like analogy, when we do not understand the grammar of the language, we may be making egregious blunders while thinking we are speaking with the utmost accuracy.