1. I wrote the essay. (active voice)

2. The essay was written by me. (Passive voice)

3. The essay will be written. (Passive voice)

Although the verb is in the active or passive voice, notice that the words active and passive describe the subjects of the sentences. That is, in the first sentence, the verb wrote is in the active voice; the subject I acts. In the second and third sentences was written and will be written are in the passive voice; the subject essay is acted upon. Notice as well the following:

When you are revising, take a good look at each sentence in which you have used the passive voice. If the passive voice clarifies your meaning retain it; if it obscures your meaning, change it. More often than not, the passive voice obscures meaning.

The revolver given Amy by the stranger is left in the desk drawer. (Left by whom? The passive voice obscures here.)

Amy leaves the stranger's revolver in the desk drawer.

When is it appropriate to use the passive voice? As I said above, it is appropriate to use the passive voice when it clarifies your meaning. Here is an appropriate example:

"In the past three decades, interest in the discipline of communication has grown rapidly." ("Has grown" is passive, but it has the advantage of putting the emphasis on the discipline of communication as I intended. I could say that "In the past three decades, more and more people have become interested in the discipline of communication," and while this is a perfectly grammatical sentence, it puts the emphasis on "more and more people.")

Finally, make every effort to avoid the Academic Passive, a particularly nefarious style of writing illustrated in the following example:

"In this paper it has been shown that..."

Very often a writer will attempt to achieve scientific objectivity with this form of writing, but "I" is usually preferable to such cumbersome and stuffy writing:

"In this paper I have shown that..."

The basic formula for a sentence using an active-verb construction is as follows:

An example would be:

The formula for a passive-verb construction is as follows:

An example would be:

If only for the sake of using fewer words, then, the active voice is ordinarily preferable to the passive voice.