Verbs relay action or a state of being and are one of two elements necessary to make a sentence. Verb choice and sentence construction determine whether sentences are active or passive in voice. Active verbs carry out the actions of the subject. Sentences written in the active voice tend to be more direct and less wordy. Many writers believe the active voice to be more engaging, while other writers believe active verbs lack the subtlety in meaning that passive sentences may deliver.
In the active voice, the subject takes the action, for instance: The author read aloud the last 100 pages. In the passive voice, the emphasis is placed not on the noun that took the action but on the noun that received the action, for example: The last 100 pages were read aloud by the author. The subject and object of the sentence are often switched when changing from the active to the passive voice.
Active verbs can usually be recognized if they are stated in an action form such as run, jump, or hide. These verbs in the past tense are also active verbs: ran, jumped, and hid. Active verbs usually directly follow the subject: John runs; John ran.
Passive verbs are often constructed by using the to be form of the active verb with the past participle of the main verb. An example of an active sentence would be: I painted the bus. In the passive verb form, the sentence becomes: The bus was painted by me.
Legal or scientific articles tend to use the passive voice more frequently. The active voice may appear as too personal in these environments. A scientist may be more comfortable with the passive sentence: The solution was prepared. In scientific circles, use of active verbs sometimes may appear as self-promotion or improper emphasis: I prepared the solution.
A passive voice may be preferable when the object of the active version of the sentence should be emphasized rather than the subject. The emphasis is on the defendant being at a certain place in the following sentence: The defendant was seen leaving the area by the witness. The active version of this sentence might make a listener focus on the witness rather than the defendant: The witness saw the defendant leaving the area.