What’s the difference between common and proper nouns?
A common noun is not capitalized, as it names a category of person, place, thing, or concept. Common nouns often require articles (e.g., “a”) or determiners (e.g., “many,” “his”).
In contrast, a proper noun is capitalized and names a specific person, place, thing, or concept. Most common nouns don’t require an article, but some require “the” (e.g., “the Great Lakes”).
The same goes for proper adjectives (e.g., “my Indian colleague”) and common adjectives (e.g., “the blue house”).