The document discusses the passive voice in English. The passive voice puts the object of the sentence before the verb and introduces the subject with "by". Some reasons to use the passive voice are to change the focus of the sentence, when the subject performing the action is unknown, unimportant or obvious, for factual or scientific writing, and to improve style. The passive is formed by putting the verb "to be" in the tense of the active verb and adding the past participle of the main verb.