World-systems theory, pioneered by sociologist Immanuel Wallerstein, is a macro-level perspective that emphasises the interconnections and interdependence among countries based on the historical expansion and current functioning of a global capitalist world economy. This theory posits that the world economy is not a collection of independent national economies but rather a single, integrated system characterised by a global division of labor and a hierarchical structure consisting of three main categories of countries: core countries, which are the wealthy, industrialised nations that dominate the global economy and control advanced technology and capital; semi-peripheral countries, which occupy an intermediate position, often supplying labor and raw materials to the core and serving as a buffer between the core and the periphery, with some level of industrialisation and potential for upward or downward mobility within the system; and peripheral countries, which have a marginal role in the world economy, often specializing in the production of raw materials and agricultural goods for the core, and are thus economically dependent on and often exploited by the core countries in unequal trading relationships. This theory highlights how the dynamics of the global capitalist system shape the economic development and social structures of nations within it, emphasizing historical processes of colonialism and neocolonialism in creating and maintaining global inequalities.