This document provides an overview of demand, including the circular flow diagram, demand schedules, the law of demand, demand curves, market demand, changes in demand versus changes in quantity demanded, and factors that cause changes in demand such as number of buyers, tastes and preferences, income, prices of other goods, availability of credit, and expectations about future prices. It explains that a change in demand is a shift of the entire demand curve, while a change in quantity demanded is a movement along the existing demand curve caused by a change in price.