In a sentence, when the subject is acting out the verb (or action), the verb is in active voice
. When the subject becomes the target of the verb (or action), the verb is in passive voice
. The dog chased the cat
is active, but The cat was chased by the dog
is passive. Aaron cuts my hair
is active, but My hair is cut by Aaron
is passive. The stock market crash caused the Depression
is active, but The Depression was caused by the stock market crash
is passive. Jacob loves Kristin
is active, but Kristin is loved by Jacob
is passive. Get it?
In passive sentences, the subject and the direct object switch places. Passive sentences, by their nature, are less compelling than active ones, so you should avoid them wherever possible. To make your sentences strong, your verbs should be action-oriented.