Teaching German at all levels, I am regularly tasked to explain cases to my students who tend to see them as an alien concept, but cases in German are easily explained. German has four cases: nominative, accusative, dative and genitive. Genitive is the easiest: it donates possession. The nominative case is reserved for the subject of a sentence, the person or thing that decides how a verb is conjugated. The accusative is the person or thing that is receiving the action of the verb – it is the object of the sentence. The dative is the beneficiary (indirect object) of any action in a sentence. English also has cases but nouns are no longer declined dependent on case. Look at this simple sentence for example:
I am making breakfast for my wife’s parents.
The subject is ‘I’ – I am left to do the work. The indirect object is ‘my wife’s parents’ – the beneficiary – they are going to eat the breakfast. The direct object is the breakfast – that is what is being made. And the genitive is my wife – because she is the one to whom the parents ‘grammatically’ belong.
Think German is complicated? Try learning Russian with six cases or Polish, which has seven cases.