• Nominative: Subject (who or what is doing the action)
• Accusative: Direct object (who or what is directly affected)
• Dative: Indirect object (to whom or for whom something is done)
• Genitive: Possession or close relationship ("of" something)

Nominative Case

• Usage: Marks the subject of a sentence—the person or thing performing the action.
• Key Question: Wer? (Who?) or Was? (What?)
• Example: Der Hund schläft. (The dog sleeps.)

Accusative Case

• Usage: Marks the direct object—the person or thing directly affected by the action.
• Key Question: Wen? (Whom?) or Was? (What?)
• Changes: The articles for masculine nouns change to den; others remain the same.
• Example: Ich sehe den Hund. (I see the dog.)

Dative Case

• Usage: Marks the indirect object—the person or thing receiving something or benefiting from the action.
• Key Question: Wem? (To whom?) or Für wen? (For whom?)
• Changes: Articles change to dem (masc./neut.), der (fem.), den (plural), and nouns often add -n in plural.
• Example: Ich gebe dem Mann einen Apfel. (I give the man an apple.)

Genitive Case

• Usage: Expresses possession or relationships—similar to "’s" or "of" in English.
• Key Question: Wessen? (Whose?)
• Changes: Masculine and neuter nouns often add -s or -es; articles change to des (masc./neut.) and der (fem./pl.).
• Example: Das ist das Buch des Lehrers. (That is the teacher’s book.)

Summary Table

Key Points

• Always identify the noun’s role in the sentence first.
• Then apply the correct case endings to articles, nouns, and pronouns.
• Some prepositions and verbs require specific cases.
• German word order is more flexible but cases clarify meaning.