This document discusses syntax and syntactic categories. It defines syntax as the study of sentence patterns and rules that determine word order and structure in a language. There are various syntactic categories including parts of speech, phrases, and sentences. Phrases are groups of words that function as a unit, and there are five main types: noun phrases, verb phrases, adjective phrases, adverb phrases, and preposition phrases. Phrase structure trees are used to represent syntactic categories and the hierarchical structure of phrases in a sentence. Basic phrase structure rules are provided.