The document explains the concept of demand in economics, defining it as the quantity of a commodity consumers are willing to purchase at a given price over a specific period. It discusses market demand, the demand curve, and introduces the law of demand, which states that price and quantity demanded are inversely related, along with exceptions like Giffen and Veblen goods. Additionally, various factors influencing demand, such as consumer income, tastes, price of related goods, expectations, advertising, and population growth are outlined.