Popular sovereignty is the principle that the authority of a government is created and sustained by the consent of its people. This means that the power to govern comes from the citizens, who have the right to make decisions about their own governance. It is a foundational concept in democratic systems, ensuring that the government reflects the will of the people. In the context of the United States, popular sovereignty played a significant role in debates over issues like slavery in the 19th century. The idea was that territories could decide for themselves whether to allow slavery, highlighting the importance of individual rights and democratic participation in shaping laws and policies.