The Age of Enlightenment, or simply The Enlightenment, is a term used to describe a time in Western philosophy and cultural life, centered upon the eighteenth century, in which reason was advocated as the primary source and legitimacy for authority.

Developing more or less simultaneously in Germany, France, Great Britain, the Netherlands, Italy, Spain, and Portugal, and buoyed by the North American colonists' successful rebellion against Great Britain in the American War of Independence, the culmination of the movement spread through much of Europe, including the Polish-Lithuanian Commonwealth, Russia and Scandinavia, along with Latin America and instigating the Haitian Revolution. It has been argued that the signatories of the American Declaration of Independence, the United States Bill of Rights, the French Declaration of the Rights of Man and of the Citizen, and the Polish-Lithuanian Constitution of May 3, 1791, were motivated by "Enlightenment" principles.