All verbs have the active voice.
With transitive verbs, a direct link between a subject and an object is realised.
With intransitive verbs, the subject can be both the doer of an action or the recipient of a change of state.
For example:
Transitive verb: Io ho venduto la mia automobile. I sold my car.
Intransitive verb: Io ho camminato molto. I walked so far.
Intransitive verb: Io sono andato a casa. I went home.
Only transitive verbs have the passive voice.
In the passive voice, the object of the active voice becomes the subject and the subject (mentioned or not) becomes a passive agent.
The verb changes adding the auxiliary verb ‘essere’ (to be) along with the past participle of the main verb.
The past participle must always agree with the gender and number of the passive subject.
For example:
io vendo il libro > il libro è venduto da me
io vendo la macchina > la macchina è venduta da me
io ho venduto il libro > il libro è stato venduto da me
io ho venduto la macchina > la macchina è stata venduta da me
The passive voice can be also realised with ‘SI passivante’ (passive SI), when the subject is undefined (we all, they all, everyone, no one, etc.)
In questo negozio si vendono automobili. They sell cars in this shop.
Ogni tanto si sente un rumore strano. Now and then you can hear a strange noise.
In the middle or reflexive voice, the subject performs the action on itself (directly or indirectly).
This fact is highlighted using a reflexive pronoun that matches the subject of the verb in both number (singular or plural) and person (first, second, or third).
Io mi lavo le mani. I wash my hands.
Reflexive verbs use the auxiliary verb ‘essere’ (to be). The past participle must always agree with the gender and number of the subject.
Francesco si è allenato duramente. Francesco has been training very hard.
Francesca si è allenata duramente. Francesca has been training very hard.
Reflexive verbs are mostly transitive verbs used in the middle voice.
For example:
Lavare To wash
Active voice: Io lavo la macchina.
Passive voice: La macchina è lavata da me.
Middle voice: Io mi lavo.
In Italian, a lot of verbs use the reflexive pronouns in the active voice too. These verbs are called pronominal verbs.
For example, the verb ‘dividere’ (to divide or to split) can be both transitive and pronominal intransitive:
Transitive: Io divido la torta in parti uguali. I divide the cake into equal parts.
Pronominal intransitive: Noi ci siamo divisi. We split up.