We use the active form to say what the subject does.

  • He drove the car yesterday.
  • I clean my house once a week.

We use the passive form to say what happens to the subject.

  • The car was driven by somebody else yesterday.
  • The house was cleaned only yesterday

Sometimes when we use the passive we do not know who did the action.

  • My watch was made in Switzerland.
  • My car has been damaged.

Sometimes we know who did something but it is not as important as what was done.

  • It was sent by Harry yesterday.
  • I was told by Sarah.

Often we use the passive to bring the topic we are interested in to the front of the sentence.

  • The vegetables are all grown by local farmers.
  • This door should be replaced when you have time.
  • This weblog is updated by MJ