Explain what a market is by giving a definition of the term “market” in expressions like “the market for wheat,” “the U.S. market for anaesthesiologists,” and “the market for the common stock of company X.” Explain why your definition is broad enough to apply to these markets and to other markets as well and is also narrow enough to exclude things that are not markets. A good definition captures the most essential features that the markets listed above have in common. If the defining characteristics in your definition change, the market should change.