Grammatical voicegrammar, is the relationship between the action or state expressed by a verb, and its arguments (subject, object, etc.).
When the subject is the agent or actor of the verb, the verb is said to be in the active voice. When the subject is patient, target or undergoer of the action, it is said to be in the passive voice. For example, "The cat ate the mouse" is active, but "The mouse was eaten by the cat" is passive.
In a passive voice sentence, the subject and the direct object switch places. The direct object is promoted to subject, and the subject is demoted to a complement (that may be left out).
In English, the passive voice is a periphrastic construction, i .e. it's modelled using an ad hoc phrase structure with a different word order, an auxiliary verb and a participle of the main verb. In other languages the passive voice is simply marked on the verb as an inflection.
Some languages (e. g. Sanskrit and Classical Greek) have a "middle voice". An intransitive verb that appears active but expresses a passive action characterizes the English middle voice. For example, in "The casserole cooked in the oven", "cooked" is syntactically active but semantically passive, putting it in the middle voice.
Many deponent verbs in Latin are also survivals of the Indo-European middle voice; many of these in turn survive as obligatory pseudo-reflexive verbs in the Romance languages such as French and Spanish.
Some languages have even more grammatical voices. For example, in Classic Mongolian there are five voices: active, passive, causative, reciprocal and cooperative.
Ergative languages usually don't have a passive voice, since their syntactic structure doesn't agree with it; instead some have an antipassive voice that deletes the object of transitive verbs.
Usage of the English passive voice
Some people consider it bad practice to use the passive voice in English, because it obscures the subject. There is a difference in approach between the UK and the USA. In the UK passive voice is commonly used. In the USA people commonly use the active voice. This is especially true regarding formal and business communications.
Of course, there is still one situation where the passive will always be popular in any country. Many people find it far more appealing to write the second of these two sentences:
- I made mistakes.
- Mistakes were made.
Ditransitive verbs in English (i.e. with a subject, direct object and indirect object) can have a passive form which takes a direct object. Contrast:
- I sent a present to you or I sent you a present
- A present was sent (to you by me)
- You were sent a present (by me)