Popular sovereignty is the principle that the authority of a state and its government is created and sustained by the consent of its people, through their elected representatives (rule by the people), who are the source of all political power.
Popular sovereignty played a significant role in the development of democratic governments, particularly during the 19th century. It was a central idea in the debates over the expansion of slavery in the United States, as well as in the movements for independence in various parts of the world.