"The Theory of World Systems" is a book written by Immanuel Wallerstein, an American sociologist and leading figure in the field of world-systems theory. The book presents the concept of world-systems theory and argues that the global economy is dominated by a few powerful states, which exercise hegemony over weaker states and regions.

According to world-systems theory, the global economy is divided into Core, peripheral, and semi-peripheral states. Core States are the most powerful and developed, and they dominate the global economy through their control of capital, technology, and other resources. Peripheral states are weaker and less developed, and they are dependent on the core states for trade and investment. Semi-peripheral states are intermediate in terms of their power and development, and they often act as intermediaries between the core and peripheral states.

In the context of world-systems theory, a peripheral state is a country that is weaker and less developed, and is dependent on the core states for trade and investment. Peripheral states are typically located in the global South and are characterized by low levels of economic development and technological advancement, as well as low levels of political and social power.

Peripheral states are often disadvantaged in the global economy, as they have limited access to capital, technology, and other resources. They are often exploited by the core states, which control the global economy and extract resources and wealth from the peripheral states.

Semi-peripheral states, on the other hand, are intermediate in terms of their power and development, and are often located between the core and peripheral states. Semi-peripheral states may have some level of economic development and technological advancement, but they are still dependent on the core states for trade and investment. They often act as intermediaries between the core and peripheral states, facilitating the flow of goods, services, and capital between these regions.

Semi-peripheral states may also have a greater degree of political and social power than peripheral states, and may play a more active role in shaping the global economy and international relations. However, they are still subject to the influence and control of the core states, and may face challenges in asserting their independence and autonomy.

Wallerstein argues that the global economy is characterized by inequality and exploitation, and that the core states exercise hegemony over the peripheral and semi-peripheral states through their control of the global economy. He contends that this inequality and exploitation are fundamental to the functioning of the global economy, and that they have shaped the course of global history.

"The Theory of World Systems" is a influential and widely studied work in the field of sociology and international relations. It has helped to shape our understanding of global economic dynamics and the role of power and inequality in shaping the international system.

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