Demand refers to the quantity of a product or service that consumers are willing and able to purchase at various prices. It is a fundamental concept in economics that helps determine how much of a good or service will be sold in a market. Generally, as the price of a product decreases, the demand for it increases, and vice versa. This relationship is known as the law of demand. Factors influencing demand include consumer preferences, income levels, and the prices of related goods. For example, if the price of coffee rises, the demand for tea may increase as consumers seek alternatives. Understanding demand is crucial for businesses and policymakers to make informed decisions.