The term voice refers to the form of a verb that shows whether the subject of a sentence does an action or has an action done to it. Active voice describes a sentence in which the subject performs the action expressed by the verb. Passive voice refers to a sentence in which the subject receives the action stated by the verb.

The following examples will help in distinguishing the active voice from the pasive:

1. Jude slapped Judith (active voice); Judith was slapped by Jude (passive voice). In the first sentence, the subject (Jude) is the doer of the action and the object (Judith) is the receiver of the action. Again, the structure of the sentence is SVO: Jude (S) slapped (V) Judith (O). In the second sentence, which is in the passive voice, the subject is not the doer of the action but the receiver: Judith was slapped by Jude. Moreover, the structure of the sentence changes to SVA: Judith (S) was slapped (V) by Jude (A).
2. Okon wrote a book (active voice); A book was written by Okon (passive voice).
3. Jane will clean the office (active voice); The office will be bought by Jane (passive voice).

For a detailed audio-visual explanation, watch the following video lecture:

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