Supply and demand is an economic model of price determination in a market. It concludes that in a competitive market, the unit price for a particular good will vary until it settles at a point where the quantity demanded by consumers (at current price) will equal the quantity supplied by producers (at current price), resulting in an economic equilibrium of price and quantity.

The four basic laws of supply and demand are:
* If demand increases and supply remains unchanged, then it leads to higher equilibrium price and quantity.
* If demand decreases and supply remains unchanged, then it leads to lower equilibrium price and quantity.
* If supply increases and demand remains unchanged, then it leads to lower equilibrium price and higher quantity.
* If supply decreases and demand remains unchanged, then it leads to higher price and lower quantity.