This section will present a brief introduction to phrase structure grammar and phrase structure diagrams (or tree diagrams). While our textbook is not focused on phrase structure, this supplement may be useful to you if you are struggling with the methods of analysis described in Section 6, and it may also be of interest to students who want a more in-depth understanding of how phrases and constituents combine to build clauses from a syntactical perspective.

Syntax refers to the ways that words are meaningfully combined into phrases, clauses, and sentences. The rules that govern phrases and phrase structure within clauses can help you understand how sentences are transformed into passive voice, or how independent clauses can be transformed into dependent clauses such as relative clauses. Phrase structure can also clarify the role that a dependent clause might be playing in another clause.

Phrase structure is often represented by a phrase structure diagram, or tree diagram, which provides a visual map of the relations of words and phrases in a clause. 

You can analyze a sentence fully by identifying the form and function of each constituent, as described in this textbook, and not use phrase structure diagrams at all; however, phrase structure diagrams might help you if you are a visual learner, because they are visual representations of the linear analysis presented in sections 4, 5, and 6. And if you are interested in understanding grammar at a deeper level, phrase structure diagrams can represent the transformations that we use to make an active sentence passive, or transform an independent clause into a dependent clause, or any of the other activities we do every day to enrich our communication. While this brief introduction is not meant to provide that kind of depth, we hope you will be able to see its value and consider taking a course in Syntax in the future.

Phrase structures are especially useful in that they can demonstrate the process of analysis in a non-linear way. This process offers a better approximation of the process we use when we analyze and make meaning out of the language we hear (for more, see Pinker, Stephen, The Language Instinct: How the Mind Creates Language, 89-103).