This document discusses syntax, which is the study of sentence structure and grammatical rules in language. It defines key syntactic terms like phrases, clauses, subjects, verbs, and word order. It explains that the goal of syntax is to understand the rules common across languages. Common phrase types are defined like noun, verb, adjective, and prepositional phrases. Sentence structure and the relationships between subjects, verbs, and objects are also covered. The document concludes by defining additional syntactic concepts like constituents, construction, and immediate constituent analysis.