This document discusses parallel structure in writing. Parallel structure refers to using similar grammatical structures within sentences, such as matching parts of speech. Using parallel structure improves readability, increases understanding, and introduces rhythm. It is achieved by balancing single words with single words, phrases with phrases, and clauses with clauses. Examples are provided to illustrate parallel structure with nouns, verbs, adjectives, adverbs, prepositions, and series. The document also provides examples of correcting lack of parallel structure.