In grammar, the term <em>voice </em>refers to the relationship between the action expressed by the verb and the participants of the event, such as the subject and object. In English, there are two types of voice:
Active voice - the subject of the sentence acts upon its verb.
Passive voice - the subject of the sentence is a recipient of the action expressed by a verb.
You can see an illustration of how active voice is converted into passive voice and the opposite below: