Supply and Demand
The market price of a good is determined by both the supply and demand for it. In the world today supply and demand is perhaps one of the most fundamental principles that exists for economics and the backbone of a market economy. Supply is represented by how much the market can offer. The quantity supplied refers to the amount of a certain good that producers are willing to supply for a certain demand price. What determines this interconnection is how much of a good or service is supplied to the market or otherwise known as the supply relationship or supply schedule which is graphically represented by the supply curve. In demand the schedule is depicted graphically as the demand curve which represents the amount of goods that buyers are willing and able to purchase at various prices, assuming all other non-price factors remain the same. The demand curve is almost always represented as downwards-sloping, meaning that as price decreases, consumers will buy more of the good. Just as the supply curves reflect marginal cost curves, demand curves can be described as marginal utility curves. The main determinants of individual demand are the price of the good, level of income, personal tastes, the population, government policies, the price of substitute goods, and the price of complementary goods.
When a suppliers' costs changes for a given output, the supply curve shifts in the same direction. For example, assume that someone invents a better way of growing corn so that the cost of corn that can be grown for a given quantity will decrease. Basically producers will be willing to supply more corn at every price and this shifts the supply curve outward, an increase in supply. This increase in supply will cause the equilibrium price to decrease. The equilibrium quantity increases as the quantity demanded increases at the new lower prices. This causes the price and the quantity move in opposite directions in a supply curve shift.