Colonialism is the extension of a nation's sovereignty over territory and people outside its own boundaries, often to facilitate economic domination over their resources, labor, and markets. The term also refers to a set of beliefs used to legitimize or promote this system, especially the belief that the mores of the colonizer are superior to those of the colonized.

Advocates of colonialism argue that colonial rule benefits the colonized by developing the economic and political infrastructure necessary for modernization and democracy. They point to such former colonies as the United States of America, Canada, Australia, New Zealand, Hong Kong and Singapore as examples of post-colonial success. These nations do not, however, represent the normal course of colonialism in that they are either settler societies, or tradepost cities.

Dependency theorists such as Andre Gunder Frank, on the other hand, argue that colonialism actually leads to the net transfer of wealth from the colonized to the colonizer, and inhibits successful economic development.

Critics of colonialism such as Frantz Fanon and Aime Cesaire argue that colonialism does political, psychological, and moral damage to the colonized as well.

More critically, Indian writer and political activist Arundhati Roy said that debating the pros and cons of colonialism/imperialism "is a bit like debating the pros and cons of rape".

Critics of the alleged abuses of economic and political advantages accruing to developed nations via globalised capitalism have referred to them as neocolonialism, and see them as a continuation of the domination and exploitation of ex-colonial countries, merely utilizing different means.

http://en.wikipedia.org/wiki/Colonialism

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I say bad!