How to differential between Common Nouns and Proper Nouns?

Question

Both nouns seem to look alike.

Answer 1

Common Nouns and Proper Nouns do look alike, but Proper Nouns identify specific people and places by their official names. For example: the girl, common; Sarah, proper. Or the city, common; Boston, proper.When they refer to high level significations, they are also proper. For example: the businessman, common; the United States President, proper.

Answer 2

I just want to emphasize Barbara’s excellent point about titles and when to capitalize them (the president vs. President Roosevelt, and my doctor vs. Dr. Martin, for example). This extends to many instances that can be tricky- one I encounter frequently is a subject (biology) vs. a specific class (AP Biology). To reiterate, a noun becomes proper when it is no longer general; once it is identifying a person, class, etc that is specific, it must be capitalized.

Answer 3

Notice, in the other Barbara’s examples, the one way common and proper nouns do not look alike: Proper nouns are always given initial capitals.

It does sometimes get confusing. “President” and other titles are now not always capitalized, but only when given as the full title, such as in Barbara’s example, or attached to the name of a specific person, such as President Lincoln. But even when it refers to the person who is currently in office, if it’s only identifying the person, and not an official action, it doesn’t get capitalized: She unfollowed the president’s Twitter account.

Are there some partiular nouns that are giving you trouble?