The passive is a verb form used to describe processes and conditions. The passive changes the perspective on an event: Whereas an active sentence emphasizes who or what something is or does, the passive emphasizes what is or was done. The person or agent is less important or unknown in a passive construction, with the emphasis on the event or process. The subject of the passive sentence is usually the person or thing to whom or to which something happens.

Active sentence: Ein Mann liefert das Essen.
(We are describing who is delivering the food. Ein Mann is the subject.)

Passive sentence: Das Essen wird geliefert.
(Here we are describing what is happening. It is not important who does the delivering. Das Essen is the subject.)

Usually, the subject of a passive sentence corresponds to the accusative object of an active sentence:

Active sentence: Pepes Firma entwickelt die App.

Passive sentence: Die App wird entwickelt.

Thus, we generally make the passive with verbs that can take an accusative object.

In the passive, the action is central, but sometimes, we still want to say who is doing something. In this case, we can add information using von + dative:

Die App wird von Pepes Firma entwickelt.

Creating the passive 

We make the passive with the auxiliary verb werden and the past participle. The auxiliary verb is in second position in the sentence and is conjugated. The past participle stays the same and comes at the end of the sentence.

Das Essen wird frisch gekocht.