Present and Past Passive

to talk about what happens to things or people. For example: The bread is eaten by Liz

When the cause of the action is unknown. For example:Thousands of people are killed on the roads every year - (We don't know who killed them)

When the cause of the action is not important. For example: The cakes are made in France - (It is not important who makes them)

If we want to say whodoes/did the action, we use by . For example: The criminal is caught by people