Phrase-structure grammar is a set of rules and principles that describe how words in a sentence are organized into phrases and how those phrases relate to one another. There are several synonyms for this term, including constituent structure grammar, phrase grammar, and immediate constituent analysis. These approaches aim to break down the sentence into smaller parts, known as constituents, in order to better understand its structure. This analysis can be done using tree diagrams, which then allow for the identification and labeling of different types of phrases, such as noun phrases and verb phrases. By understanding the underlying structure of sentences, grammatical errors can be corrected and meaning can be more effectively conveyed.