"what was the purpose of colonialism as it was practiced by the major european powers during eighteenth, nineteenth, and twentieth centuries? "

Below are some of the purposes of colonialism practiced by European powers.

Explanation:

Maintenance of the hegemony: Recruitment to the hegemony during those times was based on how much territory a colonial power had under its control.In order to get labor: There was cheap skilled and non-skilled labor in the colonized continents and states e.g Africa and Asia.In order to obtain slaves who they imported to their countries as labor in their plantations.Most of the colonies were unexplored, there was a lot of undiscovered minerals especially Africa which still exist to date.