The political, economic, and cultural domination of one people and territory by another, through settlement, administration, extraction, and the suppression of indigenous political authority. Colonialism in the strict modern sense names the European overseas project that began in the late 15th century — Portuguese and Spanish conquests in the Americas and along the African coasts — extended through Dutch, British, French, Belgian, German, and other European empires, and reached its territorial peak around 1914, when European powers and the United States ruled or claimed roughly 85% of the earth's land surface. Most formal European empires ended between 1945 and 1975; the structures and inequalities they built largely did not.
Several distinctions matter analytically. Settler colonialism (North America, Australia, Algeria, southern Africa, Israel/Palestine in part) involves the replacement of indigenous populations by settler societies and rests on a logic, in Patrick Wolfe's phrase, "of elimination." Extractive or administrative colonialism (much of Africa, South Asia, Southeast Asia under European rule) leaves indigenous populations in place but reorganizes their economies and political life around the metropole's needs. Internal colonialism describes structurally similar relations within a single national territory — applied variously to Black Americans, Native Americans, the Welsh and Irish under English rule, and others.
The intellectual tradition that takes colonialism as a central political fact runs from Aimé Césaire and Frantz Fanon through C.L.R. James, Du Bois, Walter Rodney, Edward Said, and the postcolonial scholarship that followed. The argument advanced by Cedric Robinson and the Racial Capitalism tradition is that European capitalism and European colonialism were not separable projects: the wealth, the labor regimes, and the racial categories of modernity were forged together. Decolonization, on this account, is unfinished — political independence having been won without dismantling the economic and ideological structures the colonial project laid down.