In The Associated Press Guide to Punctuation (Basic Books, 2004), Rene Cappon calls capitalization a "squishy" subject that "lacks logic":

Capitalization is largely arbitrary, a matter of style and preferences, which vary among publications.

But then logic isn't the point of capitalization; the goal is consistency, and that's important enough.

In our Guidelines for Using Capital Letters, we've tried to impose some consistency by drawing on rules spelled out in several popular style manuals, including The Associated Press Stylebook (2011), The Chicago Manual of Style (2010), and The Cambridge Guide to English Usage (2004).

To test your familiarity with these somewhat arbitrary rules, edit the following sentences to correct any errors in capitalization. Then compare your responses with the answers on page two.

 

1. "You must realize," she said, "That no one is born a criminal."
2. Every Winter, my friend Sam heads out into the Mojave desert and sings Bob Dylan songs by the light of the moon.
3. We searched the internet for the best deal on a Toshiba DVD player.
4. Before going to bed, the children watched the movie Back To The Future and read the book Where the Wild Things are.
5. In her first semester at college, my sister enrolled in four courses: Calculus, French, Political Science, and English.
6. Bernice took a kleenex from her purse and wiped the chocolate off her son's PlayStation console.
7. My Father smoked Marlboros, drank tequila, and rooted for the New York Mets.
8. My Girlfriend was brought up on a farm in wisconsin by her Aunt Katie and Uncle Bill.
9. Sent to live with her Aunt and Uncle in Atlanta, Georgia, Cara felt out of place in the big city.

1. From 1969 to 2003, the supersonic airliner Concord flew regular Transatlantic flights from London to New York.

 

Also see: Practice in Using Capital Letters.