What does common noun mean?

A common noun is a general word for any person, place, thing, or idea.

A proper noun is the name of a specific person, place, thing, or idea. Examples:

common noun: doctor

proper noun: Dr. Christiaan Barnard

common noun: continent

proper noun: Africa

common noun: tower

proper noun: Eiffel Tower

common noun: redemption

proper noun: The Shawshank Redemption