Nouns are a fundamental part of Korean grammar. They represent people, places, things, or abstract concepts. Unlike in English, Korean nouns do not have grammatical categories such as gender or number. However, they do have a distinction between countable and non-countable nouns.

Countable nouns, known as 계사애 (gyesawa-e), can be counted and take numerical markers such as 개 (gae) or 명 (myeong) to indicate quantity. For example, 개 (dog) can be expressed as 개 하나 (one dog) or 개 두 마리 (two dogs).

Non-countable nouns, known as 불계사암 (bulgyesasam), cannot be counted and do not require numerical markers. Examples include 사랑 (love) or 물 (water).

Korean nouns can also be further categorized into proper nouns and common nouns. Proper nouns refer to specific entities such as names of people, places, or organizations. Proper nouns are typically written in capitalized letters such as 김철수 (Kim Chul-Soo) or 서울 (Seoul).

Common nouns, on the other hand, refer to general entities that do not require capitalization. Examples include 책 (book) or 음식 (food).

Understanding noun theory is essential for forming sentences and expressing oneself accurately in Korean.