What is the Nominativ case?

In German grammar, the nominative case is the basic form of the noun. The subject in a given sentence is always in the nominative case.

How do you find a subject?

Let us look at a simple sentence for this.

Deu: Er schläft
Eng: He sleeps

In this sentence, the action is sleep. To find the subject in the sentence, you need to ask the question, "Who is doing the action?". We get the solution as "Er". So, Er is the subject of this sentence.

If I take another example,

Deu: Das Auto ist schön
Eng: The car is beautiful

In the above sentence, it makes no sense to ask the question "Who" here. We should ask, "What is beautiful?" in this context. We get the subject as "Das Auto".

Structure of a Simple Sentence

The structure of a simple sentence is:
<Subject> + <Conjugated form of the Verb>

The subject will be in the nominative form of the noun.

Another point to note here is that the verb conjugation is based on the subject in the sentence.

The subject in a sentence can be the name of a person, a thing, or a personal pronoun.

Personal pronouns in nominativ case

Conclusion

We understood what a nominative case is, and how to find the subject in a sentence. To find a subject, we need to ask "Who is doing the action/What is?"