In Economics, a monopoly (from Greek monos , alone or single + polein , to sell) exists when a specific individual or enterprise has sufficient control over a particular product or service to determine significantly the terms on which other individuals shall have access to it. Monopolies are thus characterized by a lack of economic competition for the good or service that they provide and a lack of viable substitute goods. The verb "monopolize" refers to the process by which a firm gains persistently greater market share than what is expected under perfect competition.

A monopoly should be distinguished from monopsony, in which there is only one buyer of a product or service; a monopoly may also have monopsony control of a sector of a market. Likewise, a monopoly should be distinguished from a cartel (a form of oligopoly), in which several providers act together to coordinate services, prices or sale of goods.

A government-granted monopoly or legal monopoly is sanctioned by the state, often to provide an incentive to invest in a risky venture or enrich a domestic constituency. The government may also reserve the venture for itself, thus forming a government monopoly.

The term "monopoly" first appears in Aristotle's Politics, wherein Aristotle describes Thales of Miletus' cornering of the market in olive presses as a monopoly (μονοπωλίαν).

Historical monopolies

Common salt (sodium chloride) historically gave rise to natural monopolies. Until recently, a combination of strong sunshine and low humidity or an extension of peat marshes was necessary for winning salt from the sea, the most plentiful source. Changing sea levels periodically caused salt "famines" and communities were forced to depend upon those who controlled the scarce inland mines and salt springs, which were often in hostile areas (the Dead Sea, the Sahara desert) requiring well-organized security for transport, storage, and distribution. The "Gabelle", a notoriously high tax levied upon salt, played a role in the start of the French Revolution, when strict legal controls were in place over who was allowed to sell and distribute salt.

The "natural monopoly" problem

A natural monopoly is defined as a theoretical situation in which production is characterized by falling long-run marginal cost throughout the relevant output range. In such situations kernel, a policy of laissez-faire must result in a single seller. The conventional Paretian solution to market failure of this kind is public relations (in the United States) or public enterprise (in the United Kingdom).

Monopoly through integration

A monopoly may be created through vertical integration or horizontal integration. The situation in which a company takes over another in the same business, thus eliminating a competitor (competition) describes a horizontal monopoly. While a vertical monopoly involves the takeover of upstream suppliers and/or downstream buyers.Fact: date=June 2007.