The document discusses the concept of supply in economics. It states that supply is the quantity of a good that is available and that quantity supplied generally increases with rising prices as firms seek to earn more revenue. It also notes that firms may decrease production if prices fall. The document introduces the concepts of a supply schedule and supply curve to illustrate the relationship between price and quantity supplied. It defines elasticity of supply and explains that an elastic supply is very responsive to price changes while an inelastic supply is not very responsive to price changes.