The document discusses the passive voice in English grammar. It is divided into active and passive voice. The passive voice is used when we want to emphasize the object or when the subject is unknown. It then provides examples of using the passive voice in simple present, past, and future tenses as well as continuous, perfect, and modal auxiliary verbs. The passive voice always uses "by" to introduce the passive object, but it can be omitted when the subject is obvious or unimportant.