In economics, a shortage or excess demand is a situation in which the demand for a product or service exceeds its supply in a market. It is the opposite of an excess supply (surplus). Definitions In a perfect market (one that matches a simple microeconomic model), an excess of demand will prompt sellers to increase prices until demand at that price matches the available supply, establishing market equilibrium. In economic terminology, a shortage occurs when for some reason (such as government intervention, or decisions by sellers not to raise prices) the price does not rise to reach equilibrium. In this circumstance, buyers want to purchase more at the market price than the quantity of the good or service that is available, and some non-price mechanism (such as "first come, first served" or a lottery) determines which buyers are served. So in a perfect market the only thing that can cause a shortage is price. In common use, the term "shortage" may refer to a situation where most people are unable to find a desired good at an affordable price, especially where supply problems have increased the price. "Market clearing" happens when all buyers and sellers willing to transact at the prevailing price are able to find partners. There are almost always willing buyers at a lower-than-market-clearing price; the narrower technical definition doesn't consider failure to serve this demand as a "shortage", even if it would be described that way in a social or political context (which the simple model of supply and demand does not attempt to encompass). Causes Shortages (in the technical sense) may be caused by the following causes: Price ceilings, a type of price control which involves a government-imposed limit on the price of a product or service. Anti-price gouging laws. Government ban on the sale of a product or service, such as prostitution or certain recreational drugs. Decisions by suppliers not to raise prices, for example to maintain friendly relationships with potential future customers during a supply disruption. Artificial scarcity. Worker shortages in low-wage industries (hospitality and leisure, education, health care, rail transportation, aviation, retail, manufacturing, food, elderly care) caused by excessively low salaries (relative to the domestic cost of living) and adverse working conditions (excessive workload and working hours), which collectively lead to occupational burnout and attrition of existing workers, insufficent incentives to attract the inflow supply of workers (through a voluntary exchange), short-staffing at