Definition: A closed question is a question that asks for an answer from a limited set of responses, such as yes or no, or a choice between options. It gets a quick, definite answer but little extra detail. Phrases like "Do you have" or "Would you accept" usually signal a closed framing.
So what? Closed questions are useful for confirming facts and getting decisions, but they can shut a conversation down. Knowing when a question is closed helps testers choose it on purpose rather than by habit.
Examples: "Do you have any questions?", which tends to get a "no" from an audience put on the spot. "Would you accept $50?" in a negotiation, where the answer opens a follow-up about why.