The nominative case in German is used primarily for the subject of a sentence – the noun or pronoun that performs the action of the verb. Here’s a brief overview of how it works:

 The nominative case in German is used primarily for the subject of a sentence – the noun or pronoun that performs the action of the verb. Here’s a brief overview of how it works:

### Key Features of the Nominative Case:

1. **Usage**:

   - The subject of a sentence (who/what is doing something).

   - Predicate nominatives (when the subject is linked to a noun via a verb like “to be”).

2. **Articles**:

   - **Definite Articles**:

     - Masculine: der (the)

     - Feminine: die (the)

     - Neuter: das (the)

     - Plural: die (the)

   - **Indefinite Articles**:

     - Masculine: ein (a/an)

     - Feminine: eine (a/an)

     - Neuter: ein (a/an)

     - Plural: keine (no/none)

3. **Pronouns**:

   - Ich (I)

   - Du (you, informal)

   - Er (he)

   - Sie (she)

   - Es (it)

   - Wir (we)

   - Ihr (you, plural informal)

   - Sie (they)

   - Sie (you, formal)

### Example Sentences:

1. **Subject**:

   - *Der Hund läuft.* (The dog runs.)

   - Here, *der Hund* is the subject in the nominative case.

2. **Predicate Nominative**:

   - *Das ist ein Lehrer.* (That is a teacher.)

   - In this case, *ein Lehrer* is describing the subject and is also in the nominative case.

### Summary:

Understanding the nominative case is essential for constructing correct sentences in German. It helps indicate the subjects and their attributes effectively. If you're interested in how it interacts with other cases (accusative, dative, genitive), let me know!