According to Wallerstein's World Systems Theory, how many tiers does the world economy have?

Wallerstein's World Systems Theory posits that the world economy is divided into three distinct tiers or categories: the core, semi-periphery, and periphery.

The core comprises highly developed nations with strong economies, advanced technologies, and significant political power, allowing them to dominate the global economic structure. The semi-periphery includes countries that are in transition; they may have some features of the core but also exhibit characteristics of the periphery. Finally, the periphery consists of the least developed nations that are largely dependent on and exploited by the core, providing raw materials and labor while receiving minimal benefit from global capitalist dynamics.

This three-tier structure helps to explain the inequalities present in the global economy, facilitating a better understanding of the relationships between different countries and how their economic positions affect their development and influence on the world stage.