The Nominative case (Yalın Hal) is the basic, dictionary form of a noun. It does not take any case suffix.

Functions of the Nominative Case:

• Subject of a sentence: The noun performing the action or being described.
• Indefinite direct object: When the direct object is non-specific ("a book" vs. "the book").
• Predicate nominative: After the verb "to be" (imek - though often implied or using suffixes like -dir) to identify or describe the subject.

Examples:

• Kedi uyuyor. (The cat is sleeping.) - "Kedi" is the subject.
• Çocuk kitap okuyor. (The child is reading a book.) - "Çocuk" is the subject; "kitap" is an indefinite direct object.
• Bu bir masa. (This is a table.) - "Masa" is a predicate nominative.
• Öğretmen geldi. (The teacher came.) - "Öğretmen" is the subject.

Essentially, if a noun is just named or is the subject acting in the sentence without specific direction, location, or possession directly marked on it by a case suffix, it's in the nominative case.