This document discusses the key concepts of grammar. It defines grammar as the system of language that describes how words are combined and organized to make meaning. Grammar includes parts of speech, their uses, forms, functions, and grammatical structures. It explains that grammar indicates what parts of speech are used to express language and the order of those parts. Specifically, it refers to the use or function of expressing meaning, the form or way words are structured, and the grammatical structure or part of speech. While language and grammar change over time, it is important for learners to understand grammatical structures and their uses and forms. However, teaching just grammar is not enough; it should be learned within the context of communication.