Problems with Commas

One of the most common mistakes people make with commas is putting them where they absolutely don't belong.

Don't use commas around restrictive elements.

The novel Naked Lunch was banned from the school library.
NOT The novel, Naked Lunch, was banned from the school library.

Don't separate subject from verb with a comma.

The girl in the window is not my sister.
NOT The girl in the window, is not my sister.

Don't separate a verb and a direct object or complement with a comma.

I saw immediately the mistake I had made.
NOT I saw immediately, the mistake I had made.

When your sentence includes paired elements—for example, with correlative conjunctions—don't use a comma to separate them.

I wanted either a trip to Europe or a new BMW.
NOT I wanted either a trip to Europe, or a new BMW.

If you are unsure about adding a comma, check the rules. If the answer isn't there, trust your ear to tell you when a pause is important.