What is the world systems theory?

World systems theory is a means of understanding world history, global economics, and social development within and between different nations. Roughly speaking, world-systems theory sees the world divided into different, transnational systems, whose interrelationships drive the global economy. According to world-systems theory, the world's nations are divided into three different categories, based on their socio-economic development and degree of dependence and/or exploitation of the other two. First, the "core" countries are the most economically advanced. Therefore, they are also the countries upon which the other two countries are most dependent.

Secondly, the "semi-periphery" countries are less economically advanced, and thus are dependent upon the core countries. However, these countries are still developed enough to be able to exploit the third class of country, known as the "periphery" countries. These countries receive a much small share of global wealth, and often lack core resources needed for better economic development. Many readings see the lack of development of periphery countries as a direct result of exploitation by core and semi-periphery countries.