This is a contemporary history class - Please define imperialism and Secondly, who (generally) are the Western powers, who are the non-Western societies?

This discussion question is this:

Here's a statement to consider: "Imperialism has been the most powerful force in world history over the last four or five centuries, carving up whole continents while oppressing indigenous peoples and obliterating entire civilizations." Defend or condemn the argument by giving examples of the interaction between Western industrial powers and traditional, non Western societies. Were these contacts essentially positive or negative?"

The book we use is "The world in the twentieth century from empires to nations" 7th edition from Daniel R Brower and Thomas Sanders.