A trade union (British English), labour union (Canadian English) or labor union (American English) is an organization of workers that have banded together to achieve common goals such as higher pay, increasing the number employees an employer hires, and better working conditions. The trade union, through its leadership, bargains with the employer on behalf of union members (rank and file members) and negotiates labour contracts (collective bargaining) with employers. The most common, but by no means only, purpose of these organisations is "maintaining or improving the conditions of their employment".

This may include the negotiation of wages, work rules, complaint procedures, rules governing hiring, firing and promotion of workers, benefits, workplace safety and policies. The agreements negotiated by the union leaders are binding on the rank and file members and the employer and in some cases on other non-member workers.

Originating in Europe, trade unions became popular in many countries during the Industrial Revolution, when the lack of skill necessary to perform most jobs shifted employment bargaining power almost completely to the employers' side, causing many workers to be mistreated and underpaid. Trade union organisations may be composed of individual workers, professionals, past workers, students, apprentices and/or the unemployed.

Milton Friedman (July 31, 1912 – November 16, 2006) was an American economist, statistician, and author who taught at the University of Chicago for more than three decades. He was a recipient of the Nobel Memorial Prize in Economic Sciences, and is known for his research on consumption analysis, monetary history and theory, and the complexity of stabilization policy. As a leader of the Chicago school of economics, he influenced the research agenda of the economics profession. A survey of economists ranked Friedman as the second most popular economist of the twentieth century behind John Maynard Keynes, and The Economist described him as "the most influential economist of the second half of the 20th century…possibly of all of it."

Friedman's challenges to what he later called "naive Keynesian" (as opposed to New Keynesian) theory began with his 1950s reinterpretation of the consumption function, and he became the main advocate opposing activist Keynesian government policies. In the late 1960s he described his own approach (along with all of mainstream economics) as using "Keynesian language and apparatus" yet rejecting its "initial" conclusions. During the 1960s he promoted an alternative macroeconomic policy known as "monetarism". He theorized there existed a "natural" rate of unemployment, and argued that governments could increase employment above this rate (e.g., by increasing aggregate demand) only at the risk of causing inflation to accelerate. He argued that the Phillips curve was not stable and predicted what would come to be known as stagflation. Friedman argued that, given the existence of the Federal Reserve, a constant small expansion of the money supply was the only wise policy.