the study of the cl es of words, their inflections, and their functions and relations in the sentence.(webster)

from the above definitions we find out that grammar never tells us what to say but how to say.

knowing some elements of a language grammar is of crucial importance for those who are at the beginning of language learning and it is recommended for some iranian students to know elements. in these days regarding university entrance exam in iran, and some international general english exams as tofel, and ielts, force the students to know and work on grammar.