Regime theory is a framework within international relations that focuses on the role of international institutions and norms in facilitating cooperation among states. It emphasizes how regimes, which are sets of principles, norms, rules, and decision-making procedures, help manage relationships and promote stability in various areas such as trade, security, and environmental issues. This theory connects closely with ideas from liberalism and neoliberal institutionalism, highlighting the importance of institutions in mitigating anarchy and fostering collaboration in the international system.