When should I use the accusative case?

The accusative is used for the direct object of a sentence. The direct object is the word (normally a noun) that receives the action of the verb. Example:Der Hund frisst den Toast - The dog eats the toastHere, the toast is the direct object as it is being eaten. As a result, "den" the accusative of "der" is written.Furthermore, the accusative is used after certain prepositions (e.g."für") as well as in certain (adverbial) phrases.