This document discusses subject-verb concord in English grammar. [1] It defines concord as the agreement between two grammatical units in features like plurality. [2] The most important type of concord is number agreement between subject and verb. [3] The three main principles governing concord are grammatical concord, notional concord, and proximity. Grammatical concord requires the verb to match the subject in person and number. Notional concord allows agreement based on meaning rather than form. Proximity means the verb agrees with the closer of two subjects.