When you study grammar, you are studying the structure of languages, and learning about how languages work. There are two types of grammar you can study: descriptive and prescriptive.

Descriptive grammar, on the one hand, refers to the structure of languages as they are actually used. Descriptive grammars are generally produced by linguists interested in specific languages or the nature of language in general.

Prescriptive grammar, on the other hand, refers to the structure of languages as people think they should be used. These grammars are generally developed by writing and language teachers who are responsible for instruction in standard forms of expression. They are most frequently applied to the standard written forms of language.

Western Grammar is a mix of descriptive and prescriptive grammar. The first two modules are concerned with the basic structure of Standard Written English. The remaining modules are, for the most part, prescriptive, and concern various rules which our culture generally believes should be followed.

Without doubt, grammar all by itself will not make you a good writer. There are, nevertheless, some good reasons for learning about the grammar of Standard Written English. First or all, studying it can give you some insight into the way the language works and in this way greater control of this medium of expression. Second, you can gain a better understanding of the prescriptive rules. There is nothing absolute about many of these prescriptive rules, but they are important if for no other reason than that they help to standardize written communication in our culture.

In complex societies such as ours, standardization is necessary in all kinds of areas. Consider traffic lights. There is no particular reason that red must mean stop, and green go, but imagine what would happen if we did not have some colours, on which we all agreed, to control the flow of traffic. In a similar way, the prescriptive rules for Standard Written English help to control much of the written communication in our culture.

In general, you are probably better off if you do not think too much about correct grammar when you are writing your first draft. You may become self-conscious and begin to think about the rules rather than what you have to say. The place to use this knowledge is in the editing process. There your knowledge of English grammar can prove to be a very important asset.