Voice is the category of the verb which indicates the relation of the predicate to the subject and the object. There are two main voices in English: the active voice and the passive voice.
The active voice shows that the person or thing denoted by the subject is the doer of the action expressed by the predicate. We help our friends. - Мы помогаем нашим друзьям.
The passive voice shows that the person or thing denoted by the subject is acted upon.
We were helped by our friends in our work.
В работе нам помогли наши друзья.
In passive voice we can't use intransitive verbs, link-verbs, modal verbs and some transitive verbs like - (to fit – годиться, быть в пору, to have – иметь, to like – любить, to suit – годиться, подходить и т.д.).
Middle voice - when primary transitive verb develops on intransitive middle meaning: The door opened
Reflexive Voice - when the subject is both the urgent and the recipient of the action of the same time: He dressed (himself)
Reciprocal voice - when the same actions is reciprocal passed from one urgent to another one being expressed by pl. subject: They kissed( each other)