1. Capitalization: The most reliable indicator. Proper nouns are always capitalized, while common nouns are not.
* Example: "Paris" is a proper noun, while "city" is a common noun.
2. Specificity: Proper nouns refer to unique, specific entities. Common nouns refer to general categories.
* Example: "Mount Everest" (a specific mountain) is a proper noun. "mountain" (a general category) is a common noun.
3. Context: Consider the sentence structure and meaning.
* Example: "I went to New York." "New York" is a proper noun because it's a specific place.
* Example: "I want to visit a city." "City" is a common noun because it's a general category.
4. Use of "the" or "a":
* Example: "The Statue of Liberty" (specific) is a proper noun. "A statue" (general) is a common noun.
5. Common Markers:
* People: Names (John, Mary, etc.), titles (President, Queen, etc.)
* Places: Countries, cities, towns, rivers, mountains (France, London, Mount Fuji, etc.)
* Organizations: Companies, schools, political parties (Apple, Harvard, Democrats, etc.)
* Events: Holidays, wars, historical periods (Christmas, World War II, the Renaissance, etc.)
* Books/Movies/Music: Titles (The Lord of the Rings, The Avengers, "Bohemian Rhapsody")
Remember:
* Proper nouns can be more than one word.
* Sometimes a proper noun can be used as a common noun, but the capitalization will still distinguish it.
* Context and your knowledge of the world can help you determine if a noun is proper or common.