In every sentence, there are two ways to express the action of a subject in reaction to a subject. These two ways are known as voices that constituents an active voice and a passive voice. So, what are they?
The active voice is the voice used to show that the grammatical subject of the verb is performing the action or inducing the event denoted by the verb. An example of an active voice is: 'I write a letter.'
Meanwhile, the passive voice is the voice used to show that the grammatical subject of the verb is the receiver (not the source) of the action denoted by the verb. An example of a passive voice is: ‘A letter is written by me.'
With the examples stated above, you will notice that although the meaning of the sentences is the same, their structures are different. The structures of the voices in the examples above can be explained like this:
Active Voice: Subject + Verb + Object
Passive Voice: Object + Verb + Subject
As you can see, the structure in the active voice was reversed in the passive voice.
Something else to know about the difference between an active or passive voice is that only past participle of verbs will be used as the main verb in all tenses made by a passive voice.
It is important that you avoid writing in passive voice as much as you can. Your sentences should always be constructed in an active voice.