This document defines and compares different types of grammar. It explains that descriptive grammar objectively describes a language's rules, while prescriptive grammar prescribes rules about how a language should be used. Universal grammar refers to innate linguistic properties that are shared across all human languages. Traditional grammar provides a framework for describing a language's structure and determining correct usage. The document also discusses how learning grammar is important for effective communication and language learning, as grammar provides the rules for forming sentences.