This document discusses passive and active voice in English grammar. It defines passive voice as sentences where the subject is receiving the action of the verb, rather than performing the action. The passive voice uses a form of "to be" plus the past participle of the main verb. It provides examples of active versus passive sentences. It also discusses when to use passive voice, such as when the actor is unknown, irrelevant, or being vague. It notes that passive voice is commonly used in scientific writing. The document concludes by explaining how to change sentences from active to passive voice and vice versa through rearranging parts of speech.