Nouns can refer to people, places, or things. There are different types of nouns including common nouns which refer to general categories like "teacher" or "city", proper nouns which refer to specific people, places, or things like "Mrs. Ortiz" or "New York City", abstract nouns which represent qualities or feelings like "truth" or "honor", and collective nouns which represent groups of people or things like "class" or "flock". The document provides examples of different types of nouns and categorizes common nouns, proper nouns, abstract nouns, and collective nouns.
