A common noun is the name of a thing. It represents one of a type of thing or the entire group.
When used in a sentence it will have “the”, “a” or “an” in
front of it (e.g. a cat, an elephant, a book, a library).
Fish, hand, page, staircase, jealousy, feet, shirt, party, house, street, hall, library and light are examples of common nouns.
Proper nouns are things that have a clear individual identity: they are one of a kind.
If the name is more than three words long, then the non-specific words like "it” or “and” do not have capitals (e.g. Harry Potter and the Philosopher’s Stone).
Michael Jackson, London, The United States of America, Australia, The Lion, the Witch and the Wardrobe, Romeo and Juliet and Adelaide are all examples of proper nouns.