Grammar refers to the whole system and structure of a language, usually taken as consisting of syntax and morphology, and sometimes also phonology and semantics. In English the main parts of speech are noun, pronoun, adjective, determiner, verb, adverb, preposition, conjunction, and interjection. Primarily constructed by the use of modal auxiliary can, will, shall, may, etc. . Understanding these will help with your own writing and to understand the author's meaning and word choice. Parts of speech is a category to which a word is assigned in accordance with its syntactic functions. .