World-systems theory is a multidisciplinary approach to world history and social change which emphasizes the world-system as the primary unit of social analysis. World-systems theorists argue that their theory explains the rise and fall of states, income inequality, social unrest, and imperialism.

In world systems theory, the core countries are the industrialized capitalist or imperialist countries, which depend on appropriation from peripheral countries and semi-peripheral countries. Core countries control and benefit from the global market. They are usually recognized as wealthy states with a wide variety of resources and are in a favorable location compared to other states. They have strong state institutions, a powerful military and powerful global political alliances.