In economics, a monopsony is a market structure in which a single buyer substantially controls the market as the major purchaser of goods and services offered by many would-be sellers. The microeconomic theory of monopsony assumes a single entity to have market power over all sellers as the only purchaser of a good or service. This is a similar power to that of a monopolist, which can influence the price for its buyers in a monopoly, where multiple buyers have only one seller of a good or service available to purchase from. Monopsony theory was developed by economist Joan Robinson in her book The Economics of Imperfect Competition (1933). Economists use the term "monopsony power" in a manner similar to "monopoly power", as a shorthand reference for a scenario in which there is one dominant power in the buying relationship, so that power is able to set prices to maximize profits not subject to competitive constraints. Monopsony power exists when one buyer faces little competition from other buyers for that labour or good, so they are able to set wages or prices for the labour or goods they are buying at a level lower than would be the case in a competitive market. In economic literature the term "monopsony" is predominantly used when referring to labour markets, however could be applied to any industry, good or service where a buyer has market power over all sellers. A classic theoretical example is a mining town, where the company that owns the mine is able to set wages low since they face no competition from other employers in hiring workers, because they are the only employer in the town, and geographic isolation or obstacles prevent workers from seeking employment in other locations. Other more current examples may include school districts where teachers have little mobility across districts. In such cases the district faces little competition from other schools in hiring teachers, giving the district increased power when negotiating employment terms. Alternative terms are oligopsony or monopsonistic competition.