Comma Before While
When while is used as a conjunction, it has two meanings. One meaning is related to time. In the temporal sense, while describes something that is happening at the same time as something else. The other meaning of while indicates a contrast. In this sense, it means “whereas” or “although.”
1. No Comma With While Means “At the Same Time”
Don’t use a comma before while when you’re talking about two things happening at the same time.
Correct: I decided to take a nap under my desk while everyone else was in the meeting.
Incorrect: I decided to take a nap under my desk, while everyone else was in the meeting.
2. Comma With While Means “Whereas” or “Although”
Use a comma before while in the middle of a sentence when you mean “whereas” or “although.”
Correct: I prefer chocolate cake, while my sister prefers key lime pie.
Incorrect: I prefer chocolate cake while my sister prefers key lime pie.
