Colonialism is the establishment of a colony in one territory by a political power from another territory, and the subsequent maintenance, expansion, and exploitation of that colony. The term is also used to describe a set of unequal relationships between the colonial power and the colony and often between the colonists and the indigenous peoples.
The European colonial period was the era from the 16th century to the mid-20th century when several European powers established colonies in Asia, Africa, and the Americas. At first the countries followed a policy of mercantilism, designed to strengthen the home economy at the expense of rivals, so the colonies were usually allowed to trade only with the mother country. By the mid-19th century, however, the powerful British Empire gave up mercantilism and trade restrictions and introduced the principle of free trade, with few restrictions or tariffs.
Collins English Dictionary defines colonialism as "the policy and practice of a power in extending control over weaker peoples or areas." The Merriam-Webster Dictionary offers four definitions, including "something characteristic of a colony" and "control by one power over a dependent area or people."
The 2006 Stanford Encyclopedia of Philosophy "uses the term 'colonialism' to describe the process of European settlement and political control over the rest of the world, including the Americas, Australia, and parts of Africa and Asia." It discusses the distinction between colonialism and imperialism and states that "given the difficulty of consistently distinguishing between the two terms, this entry will use colonialism as a broad concept that refers to the project of European political domination from the sixteenth to the twentieth centuries that ended with the national liberation movements of the 1960s."