This document discusses parallel structure, which is the repetition of a grammatical form within a sentence to show that ideas have equal importance. It provides examples of parallel structure using nouns, gerunds, adjectives, infinitives, past tense, and past perfect tense. The document also discusses how to check for parallel structure when using coordinating conjunctions, correlative conjunctions, and in comparison statements. It gives examples of parallel and non-parallel structures using words, clauses, lists, and items after a colon.