This essay provides a comprehensive overview of the impacts of colonialism on developing nations, analyzing the economic, political, and social consequences. It explores how colonialism, driven by the desire for trade and resource exploitation, has shaped the development of these countries. The analysis links colonialism to dependency theory, examining how the global capitalist system and unequal economic relations have perpetuated underdevelopment. The essay discusses the different types of colonialism and differentiates between developed, underdeveloped, and developing countries. It also delves into the Latin American and Neo-Marxist dependency theories, highlighting the role of foreign debt, trade, and political control in shaping the post-colonial landscape. Using a world system theory approach, the study examines the lasting effects of colonialism, providing a critical understanding of its multifaceted impacts.