The document discusses parallel structure and how to use it properly in writing. It defines parallel structure as using the same grammatical structure for elements in a list, series, or paired items to convey similar ideas. It provides examples of correct and incorrect parallel structure with verbs, nouns, adjectives, adverbs, and sentence structure. Maintaining parallel structure adds smoothness and emphasis to writing. Writers should check that each element of a list, series, or pair could stand alone as a complete sentence with the same structure.