* Common nouns refer to general, everyday things or concepts. They are not specific names.
* Proper nouns are names of specific people, places, or things. They are always capitalized.
Examples:
* Common nouns: dog, tree, city, happiness, color
* Proper nouns: Fido, Redwood National Park, New York City, Joy, (No proper noun for "color" exists)
"Color" is a general term that refers to the property of an object that can be described using terms like red, blue, green, etc. It's not the name of a specific color or object.