When household income increases, such as harvesting of agricultural products increases, salaries increased, consequently the family requests to purchase goods and services will rise. Surely the desire to purchase goods that correspond to the ability of income to buy what fits and if really needed.
Definition of the demand of a quantity of goods and services would be purchased or required by the consumer society at the level of price, time, and certain markets. While offering a number of items offered or sold by the producer to the consumer.
An explanation of the laws of supply and demand law is as follows:
a. If demand for certain goods and services increases while the number of items remain, then the price will go up.
b. If the demand for goods and services decreased, while the number of items remain, then the price will go down.
c. If the supply of goods and services multiply while the demand remains, then there is a possibility prices will fall.
d. If the supply of goods and services decreased, while the demand remains, then there is the possibility that prices will rise.
Of course the law of demand and supply law that could apply when other factors are fixed and unchanging, for example:
a. Public taste has not changed.
b. Goods and services as requested buyers and sellers that offered no replacement or nothing like it (substitutes).
Therefore, in economic terms is known ceteris paribus, which means economic interaction is always influenced by the circumstances prevailing in that area. Not an absolute economic rules, as well as with the formulation of other social sciences, influenced by the state of society, the desire of its people, government regulation and other social conditions.