What is the difference between a proper and an improper noun?

A proper noun is a noun that names a specific person, place, thing, or idea. An improper noun is a noun that does not name a specific person, place, thing, or idea.

For example, the proper noun "John" is a proper noun, while the improper noun "John" is an improper noun. The proper noun "Washington" is a proper noun, while the improper noun "Washington" is an improper noun.

Proper nouns are always capitalized, while improper nouns are always lowercase. Proper nouns are also always followed by a definite article (a, an), while improper nouns are always followed by a indefinite article (a, an).