This document discusses subject-verb agreement rules. It defines what a subject is and notes that a compound subject contains two or more nouns or pronouns joined by "and". It then lists 9 rules for determining whether a sentence requires a singular or plural verb based on whether the subject is singular or plural. These rules address subjects connected by conjunctions, collective nouns, pronouns like "everyone", phrases between the subject and verb, and contractions like "doesn't" and "don't".