Active and Passive Voice
Sentences in English can be active or passive. Verbs, correspondingly, have active and passive forms. The distinction between the active and passive voices can be tricky, but it is, essentially, quite simple.
In a sentence in the active voice, the subject is actively performing the action, and the object is receiving it. For example:
The cat ate the rat.
In this sentence, the subject cat is performing the action of eating the rat.
The passive voice, on the other hand, sees a reversal of roles. For example:
The rat was eaten by the cat. Here, the rat is the subject, but it is not actively, but passively performing the action. It is allowing the action to be performed on it. It is the object, the cat, which is actually performing the action, although syntactically it is receiving it.
Most sentences are in the active voice. The passive voice is employed when the noun that generally would have been the object, needs emphasis, or when you do not want to mention or do not know the identity of the subject.
Our house was burnt down by the mob!
Here, it is clear that the stress is on the fact that the speaker’s house has burnt down, rather than on the perpetrators of the act.
When you do not know or do not want to mention the identity of the subject:
My jewellery has been stolen.