The <u>passive voice</u> is formed by the verb <em>to be</em> into whatever tense needed and the past participle of the main verb. Whether to use the passive voice or not is a matter of style. However, some of the most frequent uses of the passive voice are:
to report actions whose author is unknown
to explain something within a scientific context
to emphasize the action or its object instead of the doer of the action.
