Demand is defined as the amount of a commodity that a consumer is willing and able to purchase at various prices during a given period. This concept goes beyond mere desire, requiring the ability and willingness to pay, and the availability of the good. For instance, a consumer might be willing to buy jeans at Birr 500 but not at Birr 900, illustrating how demand is sensitive to price and timing. Quantity demanded is the specific amount a consumer is ready to buy at a particular price. The law of demand states that, ceteris paribus, an increase in price leads to a decrease in quantity demanded, and vice versa. A demand schedule tabulates quantities demanded at different prices, while a demand curve graphically represents this relationship. The demand function mathematically expresses this as Q_d = f(P), where Q_d is the quantity demanded and P is price. Market demand aggregates individual demands at each price point. For example, if consumer-1 demands 3 kg, consumer-2 demands 5 kg, and consumer-3 demands 1 kg of oranges at Birr 5 per kg, the market demand is 9 kg. This dynamic illustrates how individual preferences shape overall market demand, influencing prices accordingly.