In active sentences, the thing doing the action is the subject of the sentence and the thing receiving the action is the object. Most sentences are active.
[Thing doing action] + [verb] + [thing receiving action]
In passive sentences, the thing receiving the action is the subject of the sentence and the thing doing the action is optionally included near the end of the sentence.
[Thing receiving action] + [be] + [past participle of verb] + [by] + [thing doing action]
Harry ate six shrimp at dinner. (active)
At dinner, six shrimp were eaten by Harry. (passive)
Mom read the novel in one day. (active)
The novel was read by Mom in one day. (passive)
The two kings are signing the treaty. (active)
The treaty is being signed by the two kings. (passive)
Active/Passive verb forms: