The Enlightenment was a period in the 18th century when thinkers applied reason and science to politics, society, and the economy. They challenged absolute monarch rule and argued that people have natural rights like liberty. Thinkers like Locke, Montesquieu, Voltaire, Rousseau, and Adam Smith developed new ideas about government, economics, and society that influenced revolutions and the growth of democracy. Their works spread new ways of thinking and challenged traditional authorities and institutions.