The document discusses the economic concept of demand. It defines demand as the quantity of a product that consumers are willing and able to purchase at various price levels. Demand is determined by factors such as price, income, tastes, and population. The law of demand states that, all else equal, demand decreases as price increases. However, there are some exceptions such as Giffen goods where demand increases with price. The document also discusses individual demand, market demand, demand curves, determinants of demand, and extensions/contractions in demand.