* Common nouns refer to general categories of people, places, or things.
* Proper nouns refer to specific, unique entities.
While "The Daily Mail" is a specific newspaper, it's not a unique entity. There are many other newspapers. The word "newspaper" itself is a common noun.
Example:
* Common noun: newspaper
* Proper noun: The Daily Mail
Therefore, "The Daily Mail" is a proper noun when referring to the specific newspaper, but the term "daily mail" is a common noun because it represents a general category of mail delivery.