Supply and demand is a basic economic concept that explains how prices are determined in a market. When the demand for a product, like apples, increases, and the supply remains the same, prices tend to rise. This happens because more people want to buy the product, making it more valuable. Conversely, if there is a surplus of apples and not enough buyers, the supply exceeds the demand. In this case, prices usually fall to attract more customers. Understanding supply and demand helps businesses and consumers make better decisions about buying and selling goods.