Noun case refers to the grammatical category that indicates the function of a noun in a sentence. Different languages use noun cases to show whether a noun is the subject, object, or shows possession. For example, in English, we primarily use word order to convey these roles, while languages like Latin or Russian use specific endings on nouns to indicate their case. There are several common noun cases, including the nominative case (for subjects), accusative case (for direct objects), and genitive case (for possession). Understanding noun cases helps clarify the relationships between words in a sentence, making communication more precise and effective.