Laissez-faire ( LESS-ay-FAIR; from French: laissez faire [lɛse fɛʁ] (listen), lit. 'let do') is an economic system in which transactions between private groups of people are free or almost free from any form of economic interventionism such as regulation and subsidies. As a system of thought, laissez-faire rests on the axioms that the individual is the basic unit in society and has a natural right to freedom; that the physical order of nature is a harmonious and self-regulating system; and that corporations are creatures of the state and therefore the citizens must watch them closely due to their propensity to disrupt the Smithian spontaneous order.

These axioms constitute the basic elements of laissez-faire thought. Another basic principle holds that markets should be competitive, a rule that the early advocates of laissez-faire always emphasized. With the aims of maximizing freedom and of allowing markets to self-regulate, early advocates of laissez-faire proposed a impôt unique, a tax on land rent (similar to Georgism) to replace all taxes that they saw as damaging welfare by penalizing production.

Proponents of laissez-faire argue for a complete separation of government from the economic sector. The phrase laissez-faire is part of a larger French phrase and literally translates to "let [it/them] do", but in this context the phrase usually means to "let it be" and in expression "laid back." Although never practiced with full consistency, laissez-faire capitalism emerged in the mid-18th century and was further popularized by Adam Smith's book The Wealth of Nations. It was most prominent in Britain and the United States during this period but both economies became steadily more controlled throughout the 19th and 20th centuries. While associated with capitalism in common usage, there are also non-capitalist forms of laissez-faire, including some forms of market socialism.