Such as Bill Gates, New York and the Hudson River. A proper noun is always capitalized. A common noun is used to name one or all members of a class or group. Such as a boat, woman, light and minutes. A common noun does not have to be capitalized.
Common nouns can be concrete or abstract.
Concrete nouns are used to name things people can use their senses to see. A pronoun is used in the place of a noun or phrase. Personal pronouns are used to refer to specific nouns. Relative pronouns introduce dependent clauses. Interrogative pronouns introduce a question.