In world-systems theory, the semi-periphery countries (sometimes referred to as just the semi-periphery) are the industrializing, mostly capitalist countries which are positioned between the periphery and core countries. Semi-periphery countries have organizational characteristics of both core countries and periphery countries and are often geographically located between core and peripheral regions as well as between two or more competing core regions. Semi-periphery regions play a major role in mediating economic, political, and social activities that link core and peripheral areas.