World-Systems Theory, primarily developed by Immanuel Wallerstein, offers a macro-sociological perspective on global history and social change. It argues that the world is not merely a collection of independent states but rather an interconnected system, primarily an economic one, driven by the capitalist pursuit of profit and accumulation. The theory emerged as a critique of modernization theory and dependency theory, proposing a holistic view of global inequality.

Its central tenets include:

1. World-System as Unit of Analysis: The fundamental unit of social analysis is not the nation-state but the 'world-system' itself, which is a self-contained, self-perpetuating economic and political entity larger than any single state.
2. Three-Tier Structure: The world-system is divided into three hierarchical zones based on their role in the global division of labor:
   • Core: Consists of the most developed, industrialized, and powerful states (e.g., Western Europe, North America). They specialize in high-profit, capital-intensive production, control global finance, and exploit the periphery.
   • Periphery: Comprises less developed, often exploited regions (e.g., many countries in Africa, Latin America). They provide raw materials, cheap labor, and agricultural products to the core, engaging in low-profit, labor-intensive production.
   • Semi-Periphery: Occupies an intermediate position (e.g., Brazil, India, China). These states exhibit characteristics of both core and periphery, acting as a buffer between the two. They may exploit the periphery while being exploited by the core, and can experience upward or downward mobility within the system.
3. Unequal Exchange and Exploitation: The core extracts surplus value from the periphery through unequal exchange, where goods from the periphery are undervalued and goods from the core are overvalued. This perpetuates underdevelopment in the periphery and accumulation in the core.
4. Capitalist Accumulation: The driving force of the world-system is the endless accumulation of capital, which dictates the economic and political interactions between the zones.
5. Historical Development: The theory traces the historical development of the capitalist world-economy from the 16th century, emphasizing its expansion and the creation of global inequalities over time.

World-Systems Theory provides a powerful framework for understanding global inequality, historical patterns of development, and the interconnectedness of economic and political power across the globe, though it has been criticized for its economic determinism and potential oversimplification of state agency.