This document discusses supply, supply curves, and factors that affect supply. It defines supply as the quantity producers are willing to sell at a given price while holding other factors constant. The supply curve is upward sloping because marginal costs increase with higher production. Changes in marginal costs, number of producers, and expectations can shift the supply curve. Supply is more elastic when it is easier and faster for businesses to change production in response to price changes. While computer prices have fallen, supply has increased, which can be explained by technological improvements lowering marginal costs of production.