Here's why:
* Common nouns are general names for people, places, or things. They are not capitalized unless they are the first word in a sentence.
* Proper nouns are specific names for people, places, or things. They are always capitalized.
For example:
* Restaurant is a general term for a place where people eat.
* The Cheesecake Factory is a specific restaurant, so it's a proper noun.
Let me know if you have any other questions!