This document discusses syntax, which is the study of the structure of phrases and sentences. It addresses two key principles of sentence organization: linear order and hierarchical structure. Linear order refers to the specific sequence of words that determine a sentence's grammaticality and meaning. Hierarchical structure refers to the way words are organized into nested constituent groupings within a sentence, with the smallest constituents being individual words and the largest being the sentence itself. Tree diagrams can be used to represent a sentence's syntactic structure and constituent relationships.