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.These regions allow for the possibility of innovative technology, reforms in social and organizational structure, and dominance over peripheral nations. These changes can lead to a semi-periphery country being promoted to a core nation. Semi-periphery is, however, more than a description, as it also serves as a position within the world hierarchy in which social and economic change can be interpreted.World-systems theory describes the semi-periphery as a key structural element in the world economy. The semi-periphery plays a vital role comparative to that of the role that Spain and Portugal played in the seventeenth and eighteenth centuries as intermediate trading groups within the European colonial empire.Today, the semi-periphery is generally industrialized. Semi-peripheral countries contribute to the manufacturing and exportation of a variety of goods. They are marked by above average land mass, as exemplified by China, India, Brazil, Mexico, and Iran. More land mass typically means an increased market size and share. Semi-peripheral nations are not all large though, as smaller countries such as Israel, Poland, and Greece exist within the semi-periphery.